# Suffix tree

Suffix tree is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.

A suffix tree is a data structure commonly used in string algorithms.

Given a string S of length n, its suffix tree is a tree T such that:

• T has exactly n leaves numbered from 1 to n.
• Except for the root, every internal node has at least two children.
• Each edge of T is labelled with a non-empty substring of S.
• No two edges starting out of a node can have string labels beginning with the same character.
• The string obtained by concatenating all the string labels found on the path from the root to leaf i spells out suffix S[i..n], for i from 1 to n.

Such a tree does not exist for all strings. To ensure existence, a character that is not found in S must be appended at its end. The character '\$' is traditionally used for this purpose.

For this task, build and display the suffix tree of the string "banana\$". Displaying the tree can be done using the code from the visualize a tree task, but any other convenient method is accepted.

There are several ways to implement the tree data structure, for instance how edges should be labelled. Latitude is given in this matter, but notice that a simple way to do it is to label each node with the label of the edge leading to it.

The computation time for an efficient algorithm should be ${\displaystyle O(n)}$, but such an algorithm might be difficult to implement. An easier, ${\displaystyle O(n^{2})}$ algorithm is accepted.

## 11l

Translation of: Python
```T Node
String sub
[Int] ch
F (sub, children)
.sub = sub
.ch = children

T SuffixTree
nodes = [Node(‘’, [Int]())]
F (str)
L(i) 0 .< str.len

V n = 0
V i = 0
L i < suf.len
V b = suf[i]
V x2 = 0
Int n2
L
V children = .nodes[n].ch
I x2 == children.len
n2 = .nodes.len
.nodes.append(Node(suf[i..], [Int]()))
.nodes[n].ch.append(n2)
R
n2 = children[x2]
I .nodes[n2].sub[0] == b
L.break
x2 = x2 + 1
V sub2 = .nodes[n2].sub
V j = 0
L j < sub2.len
I suf[i + j] != sub2[j]
V n3 = n2
n2 = .nodes.len
.nodes.append(Node(sub2[0 .< j], [n3]))
.nodes[n3].sub = sub2[j..]
.nodes[n].ch[x2] = n2
L.break
j = j + 1
i = i + j
n = n2

F visualize()
I .nodes.empty
print(‘<empty>’)
R

F f(Int n, String pre) -> Void
V children = @.nodes[n].ch
I children.empty
print(‘-- ’(@.nodes[n].sub))
R
print(‘+- ’(@.nodes[n].sub))
L(c) children[0 .< (len)-1]
print(pre‘ +-’, end' ‘ ’)
@f(c, pre‘ | ’)
print(pre‘ +-’, end' ‘ ’)
@f(children.last, pre‘  ’)
f(0, ‘’)

SuffixTree(‘banana\$’).visualize()```
Output:
```+-
+- -- banana\$
+- +- a
|  +- +- na
|  |  +- -- na\$
|  |  +- -- \$
|  +- -- \$
+- +- na
|  +- -- na\$
|  +- -- \$
+- -- \$
```

## C#

Translation of: C++
```using System;
using System.Collections.Generic;

namespace SuffixTree {
class Node {
public string sub;                     // a substring of the input string
public List<int> ch = new List<int>(); // vector of child nodes

public Node() {
sub = "";
}

public Node(string sub, params int[] children) {
this.sub = sub;
}
}

class SuffixTree {
readonly List<Node> nodes = new List<Node>();

public SuffixTree(string str) {
for (int i = 0; i < str.Length; i++) {
}
}

public void Visualize() {
if (nodes.Count == 0) {
Console.WriteLine("<empty>");
return;
}

void f(int n, string pre) {
var children = nodes[n].ch;
if (children.Count == 0) {
Console.WriteLine("- {0}", nodes[n].sub);
return;
}
Console.WriteLine("+ {0}", nodes[n].sub);

var it = children.GetEnumerator();
if (it.MoveNext()) {
do {
var cit = it;
if (!cit.MoveNext()) break;

Console.Write("{0}+-", pre);
f(it.Current, pre + "| ");
} while (it.MoveNext());
}

Console.Write("{0}+-", pre);
f(children[children.Count-1], pre+"  ");
}

f(0, "");
}

int n = 0;
int i = 0;
while (i < suf.Length) {
char b = suf[i];
int x2 = 0;
int n2;
while (true) {
var children = nodes[n].ch;
if (x2 == children.Count) {
// no matching child, remainder of suf becomes new node
n2 = nodes.Count;
return;
}
n2 = children[x2];
if (nodes[n2].sub[0] == b) {
break;
}
x2++;
}
// find prefix of remaining suffix in common with child
var sub2 = nodes[n2].sub;
int j = 0;
while (j < sub2.Length) {
if (suf[i + j] != sub2[j]) {
// split n2
var n3 = n2;
// new node for the part in common
n2 = nodes.Count;
nodes[n3].sub = sub2.Substring(j); // old node loses the part in common
nodes[n].ch[x2] = n2;
break; // continue down the tree
}
j++;
}
i += j; // advance past part in common
n = n2; // continue down the tree
}
}
}

class Program {
static void Main() {
new SuffixTree("banana\$").Visualize();
}
}
}
```
Output:
```+
+-- banana\$
+-+ a
| +-+ na
| | +-- na\$
| | +-- \$
| +-- \$
+-+ na
| +-- na\$
| +-- \$
+-- \$```

## C++

Translation of: D
```#include <functional>
#include <iostream>
#include <vector>

struct Node {
std::string sub = "";   // a substring of the input string
std::vector<int> ch;    // vector of child nodes

Node() {
// empty
}

Node(const std::string& sub, std::initializer_list<int> children) : sub(sub) {
ch.insert(ch.end(), children);
}
};

struct SuffixTree {
std::vector<Node> nodes;

SuffixTree(const std::string& str) {
nodes.push_back(Node{});
for (size_t i = 0; i < str.length(); i++) {
}
}

void visualize() {
if (nodes.size() == 0) {
std::cout << "<empty>\n";
return;
}

std::function<void(int, const std::string&)> f;
f = [&](int n, const std::string & pre) {
auto children = nodes[n].ch;
if (children.size() == 0) {
std::cout << "- " << nodes[n].sub << '\n';
return;
}
std::cout << "+ " << nodes[n].sub << '\n';

auto it = std::begin(children);
if (it != std::end(children)) do {
if (std::next(it) == std::end(children)) break;
std::cout << pre << "+-";
f(*it, pre + "| ");
it = std::next(it);
} while (true);

std::cout << pre << "+-";
f(children[children.size() - 1], pre + "  ");
};

f(0, "");
}

private:
void addSuffix(const std::string & suf) {
int n = 0;
size_t i = 0;
while (i < suf.length()) {
char b = suf[i];
int x2 = 0;
int n2;
while (true) {
auto children = nodes[n].ch;
if (x2 == children.size()) {
// no matching child, remainder of suf becomes new node
n2 = nodes.size();
nodes.push_back(Node(suf.substr(i), {}));
nodes[n].ch.push_back(n2);
return;
}
n2 = children[x2];
if (nodes[n2].sub[0] == b) {
break;
}
x2++;
}
// find prefix of remaining suffix in common with child
auto sub2 = nodes[n2].sub;
size_t j = 0;
while (j < sub2.size()) {
if (suf[i + j] != sub2[j]) {
// split n2
auto n3 = n2;
// new node for the part in common
n2 = nodes.size();
nodes.push_back(Node(sub2.substr(0, j), { n3 }));
nodes[n3].sub = sub2.substr(j); // old node loses the part in common
nodes[n].ch[x2] = n2;
break; // continue down the tree
}
j++;
}
i += j; // advance past part in common
n = n2; // continue down the tree
}
}
};

int main() {
SuffixTree("banana\$").visualize();
}
```
Output:
```+
+-- banana\$
+-+ a
| +-+ na
| | +-- na\$
| | +-- \$
| +-- \$
+-+ na
| +-- na\$
| +-- \$
+-- \$```

## D

Translation of: Kotlin
```import std.stdio;

struct Node {
string sub = ""; // a substring of the input string
int[] ch;        // array of child nodes

this(string sub, int[] children ...) {
this.sub = sub;
ch = children;
}
}

struct SuffixTree {
Node[] nodes;

this(string str) {
nodes ~= Node();
for (int i=0; i<str.length; ++i) {
}
}

int n = 0;
int i = 0;
while (i < suf.length) {
char b  = suf[i];
int x2 = 0;
int n2;
while (true) {
auto children = nodes[n].ch;
if (x2 == children.length) {
// no matching child, remainder of suf becomes new node.
n2 = nodes.length;
nodes ~= Node(suf[i..\$]);
nodes[n].ch ~= n2;
return;
}
n2 = children[x2];
if (nodes[n2].sub[0] == b) {
break;
}
x2++;
}
// find prefix of remaining suffix in common with child
auto sub2 = nodes[n2].sub;
int j = 0;
while (j < sub2.length) {
if (suf[i + j] != sub2[j]) {
// split n2
auto n3 = n2;
// new node for the part in common
n2 = nodes.length;
nodes ~= Node(sub2[0..j], n3);
nodes[n3].sub = sub2[j..\$];  // old node loses the part in common
nodes[n].ch[x2] = n2;
break;  // continue down the tree
}
j++;
}
i += j;  // advance past part in common
n = n2;  // continue down the tree
}
}

void visualize() {
if (nodes.length == 0) {
writeln("<empty>");
return;
}

void f(int n, string pre) {
auto children = nodes[n].ch;
if (children.length == 0) {
writefln("╴ %s", nodes[n].sub);
return;
}
writefln("┐ %s", nodes[n].sub);
foreach (c; children[0..\$-1]) {
write(pre, "├─");
f(c, pre ~ "│ ");
}
write(pre, "└─");
f(children[\$-1], pre ~ "  ");
}

f(0, "");
}
}

void main() {
SuffixTree("banana\$").visualize();
}
```
Output:
```┐
├─╴ banana\$
├─┐ a
│ ├─┐ na
│ │ ├─╴ na\$
│ │ └─╴ \$
│ └─╴ \$
├─┐ na
│ ├─╴ na\$
│ └─╴ \$
└─╴ \$```

## Elixir

```defmodule STree do
defstruct branch: []

defp suffixes([]), do: []
defp suffixes(w), do: [w | suffixes tl(w)]

defp lcp([], _, acc), do: acc
defp lcp(_, [], acc), do: acc
defp lcp([c | u], [a | w], acc) do
if c == a do
lcp(u, w, acc + 1)
else acc
end
end

defp g([], aw), do: [{{aw, length aw}, nil}]
defp g(cusnes, aw) do
[cusn | es] = cusnes
{cus, node} = cusn
{cu, culen} = cus
cpl = case node do
nil -> lcp cu, aw, 0
_   -> lcp (Enum.take cu, culen), aw, 0
end
x = Enum.drop cu, cpl
xlen = culen - cpl
y = Enum.drop aw, cpl
ex = {{x, xlen}, node}
ey = {{y, length y}, nil}
cond do
hd(aw) > hd(cu)          -> [cusn | g(es, aw)]
hd(aw) < hd(cu)          -> [{{aw, length aw}, nil} | cusnes]
nil != node && xlen == 0 -> [{cus, insert_suffix(y, node)} | es]
hd(x) < hd(y)            -> [{{cu, cpl}, %STree{branch: [ex, ey]}} | es]
true                     -> [{{cu, cpl}, %STree{branch: [ey, ex]}} | es]
end
end

defp insert_suffix(aw, node), do: %STree{branch: g(node.branch, aw)}

def naive_insertion(t), do: List.foldl(suffixes(t), %STree{}, &insert_suffix/2)

defp f(nil, _, label), do: IO.puts("╴ #{label}")
defp f(%STree{branch: children}, pre, label) do
IO.puts "┐ #{label}"
children
|> Enum.take(length(children) - 1)
|> Enum.each(fn c ->
IO.write(pre <> "├─")
{ws, len} = elem(c, 0)
f(elem(c, 1), pre <> "│ ", Enum.join(Enum.take ws, len))
end)
IO.write(pre <> "└─")
c = List.last(children)
{ws, len} = elem(c, 0)
f(elem(c, 1), pre <> "  ", Enum.join(Enum.take ws, len))
end

def visualize(n), do: f(n, "", "")

def main do
"banana\$"
|> String.graphemes
|> naive_insertion
|> visualize
end
end
```
Output:
```┐
├─╴ \$
├─┐ a
│ ├─╴ \$
│ └─┐ na
│   ├─╴ \$
│   └─╴ na\$
├─╴ banana\$
└─┐ na
├─╴ \$
└─╴ na\$
```

## Go

Vis function from Visualize_a_tree#Unicode.

```package main

import "fmt"

func main() {
vis(buildTree("banana\$"))
}

type tree []node

type node struct {
sub string // a substring of the input string
ch  []int  // list of child nodes
}

func buildTree(s string) tree {
t := tree{node{}} // root node
for i := range s {
}
return t
}

func (t tree) addSuffix(suf string) tree {
n := 0
for i := 0; i < len(suf); {
b := suf[i]
ch := t[n].ch
var x2, n2 int
for ; ; x2++ {
if x2 == len(ch) {
// no matching child, remainder of suf becomes new node.
n2 = len(t)
t = append(t, node{sub: suf[i:]})
t[n].ch = append(t[n].ch, n2)
return t
}
n2 = ch[x2]
if t[n2].sub[0] == b {
break
}
}
// find prefix of remaining suffix in common with child
sub2 := t[n2].sub
j := 0
for ; j < len(sub2); j++ {
if suf[i+j] != sub2[j] {
// split n2
n3 := n2
// new node for the part in common
n2 = len(t)
t = append(t, node{sub2[:j], []int{n3}})
t[n3].sub = sub2[j:] // old node loses the part in common
t[n].ch[x2] = n2
break // continue down the tree
}
}
i += j // advance past part in common
n = n2 // continue down the tree
}
return t
}

func vis(t tree) {
if len(t) == 0 {
fmt.Println("<empty>")
return
}
var f func(int, string)
f = func(n int, pre string) {
children := t[n].ch
if len(children) == 0 {
fmt.Println("╴", t[n].sub)
return
}
fmt.Println("┐", t[n].sub)
last := len(children) - 1
for _, ch := range children[:last] {
fmt.Print(pre, "├─")
f(ch, pre+"│ ")
}
fmt.Print(pre, "└─")
f(children[last], pre+"  ")
}
f(0, "")
}
```
Output:
```┐
├─╴ banana\$
├─┐ a
│ ├─┐ na
│ │ ├─╴ na\$
│ │ └─╴ \$
│ └─╴ \$
├─┐ na
│ ├─╴ na\$
│ └─╴ \$
└─╴ \$
```

## J

Implementation:

```classify=: {.@> </. ]

build_tree=:3 :0
tree=. ,:_;_;''
if. 0=#y do. tree return.end.
if. 1=#y do. tree,(#;y);0;y return.end.
for_box.classify y do.
char=. {.>{.>box
subtree=. }.build_tree }.each>box
ndx=.I.0=1&{::"1 subtree
n=.#tree
if. 1=#ndx do.
counts=. 1 + 0&{::"1 subtree
parents=. (n-1) (+*]&*) 1&{::"1 subtree
edges=. (ndx}~ <@(char,ndx&{::)) 2&{"1 subtree
tree=. tree, counts;"0 1 parents;"0 edges
else.
tree=. tree,(__;0;,char),(1;n;0) + ::]&.>"1 subtree
end.
end.
)

suffix_tree=:3 :0
assert. -.({:e.}:)y
tree=. B=:|:build_tree <\. y
((1+#y)-each {.tree),}.tree
)
```

```   suffix_tree 'banana\$'
┌──┬───────┬─┬──┬───┬─┬─┬──┬───┬─┬─┐
│__│1      │_│_ │2  │4│6│_ │3  │5│7│
├──┼───────┼─┼──┼───┼─┼─┼──┼───┼─┼─┤
│_ │0      │0│2 │3  │3│2│0 │7  │7│0│
├──┼───────┼─┼──┼───┼─┼─┼──┼───┼─┼─┤
│  │banana\$│a│na│na\$│\$│\$│na│na\$│\$│\$│
└──┴───────┴─┴──┴───┴─┴─┴──┴───┴─┴─┘
```

The first row is the leaf number (_ for internal nodes).

The second row is parent index (_ for root node).

The third row is the edge's substring (empty for root node).

Visualizing, using showtree and prefixing the substring leading to each leaf with the leaf number (in brackets):

```fmttree=: ;@(1&{) showtree~ {: (,~ }.`('[','] ',~":)@.(_>|))each {.

fmttree suffix_tree 'banana\$'
┌─ [1] banana\$
│                       ┌─ [2] na\$
│             ┌─ na ────┴─ [4] \$
────┼─ a ─────────┴─ [6] \$
│             ┌─ [3] na\$
├─ na ────────┴─ [5] \$
└─ [7] \$
```

## Java

Translation of: Kotlin
```import java.util.ArrayList;
import java.util.List;

public class SuffixTreeProblem {
private static class Node {
String sub = "";                       // a substring of the input string
List<Integer> ch = new ArrayList<>();  // list of child nodes
}

private static class SuffixTree {
private List<Node> nodes = new ArrayList<>();

public SuffixTree(String str) {
for (int i = 0; i < str.length(); ++i) {
}
}

int n = 0;
int i = 0;
while (i < suf.length()) {
char b = suf.charAt(i);
List<Integer> children = nodes.get(n).ch;
int x2 = 0;
int n2;
while (true) {
if (x2 == children.size()) {
// no matching child, remainder of suf becomes new node.
n2 = nodes.size();
Node temp = new Node();
temp.sub = suf.substring(i);
return;
}
n2 = children.get(x2);
if (nodes.get(n2).sub.charAt(0) == b) break;
x2++;
}
// find prefix of remaining suffix in common with child
String sub2 = nodes.get(n2).sub;
int j = 0;
while (j < sub2.length()) {
if (suf.charAt(i + j) != sub2.charAt(j)) {
// split n2
int n3 = n2;
// new node for the part in common
n2 = nodes.size();
Node temp = new Node();
temp.sub = sub2.substring(0, j);
nodes.get(n3).sub = sub2.substring(j);  // old node loses the part in common
nodes.get(n).ch.set(x2, n2);
break;  // continue down the tree
}
j++;
}
i += j;  // advance past part in common
n = n2;  // continue down the tree
}
}

public void visualize() {
if (nodes.isEmpty()) {
System.out.println("<empty>");
return;
}
visualize_f(0, "");
}

private void visualize_f(int n, String pre) {
List<Integer> children = nodes.get(n).ch;
if (children.isEmpty()) {
System.out.println("- " + nodes.get(n).sub);
return;
}
System.out.println("┐ " + nodes.get(n).sub);
for (int i = 0; i < children.size() - 1; i++) {
Integer c = children.get(i);
System.out.print(pre + "├─");
visualize_f(c, pre + "│ ");
}
System.out.print(pre + "└─");
visualize_f(children.get(children.size() - 1), pre + "  ");
}
}

public static void main(String[] args) {
new SuffixTree("banana\$").visualize();
}
}
```
Output:
```┐
├─- banana\$
├─┐ a
│ ├─┐ na
│ │ ├─- na\$
│ │ └─- \$
│ └─- \$
├─┐ na
│ ├─- na\$
│ └─- \$
└─- \$```

## JavaScript

Translation of: Java
```class Node {
sub = ''; // a substring of the input string
children = []; // list of child nodes
}

class SuffixTree {
nodes = [];

constructor(str) {
this.nodes.push(new Node());
for (let i = 0; i < str.length; ++i) {
}
}

let n = 0;
let i = 0;
while (i < suf.length) {
const b = suf.charAt(i);
const children = this.nodes[n].children;
let x2 = 0;
let n2;
while (true) {
if (x2 === children.length) {
// no matching child, remainder of suf becomes new node.
n2 = this.nodes.length;
const temp = new Node();
temp.sub = suf.slice(i);
this.nodes.push(temp);
children.push(n2);
return;
}
n2 = children[x2];
if (this.nodes[n2].sub.charAt(0) === b) break;
x2++;
}
// find prefix of remaining suffix in common with child
const sub2 = this.nodes[n2].sub;
let j = 0;
while (j < sub2.length) {
if (suf.charAt(i + j) !== sub2.charAt(j)) {
// split n2
const n3 = n2;
// new node for the part in common
n2 = this.nodes.length;
const temp = new Node();
temp.sub = sub2.slice(0, j);
temp.children.push(n3);
this.nodes.push(temp);
this.nodes[n3].sub = sub2.slice(j);  // old node loses the part in common
this.nodes[n].children[x2] = n2;
break;  // continue down the tree
}
j++;
}
i += j;  // advance past part in common
n = n2;  // continue down the tree
}
}

toString() {
if (this.nodes.length === 0) {
return '<empty>';
}
return this.toString_f(0, '');
}

toString_f(n, pre) {
const children = this.nodes[n].children;
if (children.length === 0) {
return '- ' + this.nodes[n].sub + '\n';
}
let s = '┐ ' + this.nodes[n].sub + '\n';
for (let i = 0; i < children.length - 1; i++) {
const c = children[i];
s += pre + '├─';
s += this.toString_f(c, pre + '│ ');
}
s += pre + '└─';
s += this.toString_f(children[children.length - 1], pre + '  ');
return s;
}
}

const st = new SuffixTree('banana');
console.log(st.toString());
```
Output:
```┐
├─- banana
├─┐ a
│ └─┐ na
│   └─- na
└─┐ na
└─- na
```

## Julia

Translation of: Go
```import Base.print

mutable struct Node
sub::String
ch::Vector{Int}
Node(str, v=Int[]) = new(str, v)
end

struct SuffixTree
nodes::Vector{Node}
function SuffixTree(s::String)
nod = [Node("", Int[])]
for i in 1:length(s)
end
return new(nod)
end
end

n, i = 1, 1
while i <= length(suf)
x2, n2, b = 1, 1, suf[i]
while true
children = tree[n].ch
if x2 > length(children)
push!(tree, Node(suf[i:end]))
push!(tree[n].ch, length(tree))
return
end
n2 = children[x2]
(tree[n2].sub[1] == b) && break
x2 += 1
end
sub2, j = tree[n2].sub, 0
while j < length(sub2)
if suf[i + j] != sub2[j + 1]
push!(tree, Node(sub2[1:j], [n2]))
tree[n2].sub = sub2[j+1:end]
n2 = length(tree)
tree[n].ch[x2] = n2
break
end
j += 1
end
i += j
n = n2
end
end

function Base.print(io::IO, suffixtree::SuffixTree)
function treeprint(n::Int, pre::String)
children = suffixtree.nodes[n].ch
if isempty(children)
println("╴ ", suffixtree.nodes[n].sub)
else
println("┐ ", suffixtree.nodes[n].sub)
for c in children[1:end-1]
print(pre, "├─")
treeprint(c, pre * "│ ")
end
print(pre, "└─")
treeprint(children[end], pre * "  ")
end
end
if isempty(suffixtree.nodes)
println("<empty>")
else
treeprint(1, "")
end
end

println(SuffixTree("banana\\$"))
```
Output:
```┐
├─╴ banana\$
├─┐ a
│ ├─┐ na
│ │ ├─╴ na\$
│ │ └─╴ \$
│ └─╴ \$
├─┐ na
│ ├─╴ na\$
│ └─╴ \$
└─╴ \$
```

## Kotlin

Translation of: Go
```// version 1.1.3

class Node {
var sub = ""                    // a substring of the input string
var ch  = mutableListOf<Int>()  // list of child nodes
}

class SuffixTree(val str: String) {
val nodes = mutableListOf<Node>(Node())

init {
for (i in 0 until str.length) addSuffix(str.substring(i))
}

var n = 0
var i = 0
while (i < suf.length) {
val b  = suf[i]
val children = nodes[n].ch
var x2 = 0
var n2: Int
while (true) {
if (x2 == children.size) {
// no matching child, remainder of suf becomes new node.
n2 = nodes.size
nodes.add(Node().apply { sub = suf.substring(i) } )
return
}
n2 = children[x2]
if (nodes[n2].sub[0] == b) break
x2++
}
// find prefix of remaining suffix in common with child
val sub2 = nodes[n2].sub
var j = 0
while (j < sub2.length) {
if (suf[i + j] != sub2[j]) {
// split n2
val n3 = n2
// new node for the part in common
n2 = nodes.size
sub = sub2.substring(0, j)
})
nodes[n3].sub = sub2.substring(j)  // old node loses the part in common
nodes[n].ch[x2] = n2
break  // continue down the tree
}
j++
}
i += j  // advance past part in common
n = n2  // continue down the tree
}
}

fun visualize() {
if (nodes.isEmpty()) {
println("<empty>")
return
}

fun f(n: Int, pre: String) {
val children = nodes[n].ch
if (children.isEmpty()) {
println("╴ \${nodes[n].sub}")
return
}
println("┐ \${nodes[n].sub}")
for (c in children.dropLast(1)) {
print(pre + "├─")
f(c, pre + "│ ")
}
print(pre + "└─")
f(children.last(), pre + "  ")
}

f(0, "")
}
}

fun main(args: Array<String>) {
SuffixTree("banana\$").visualize()
}
```
Output:
```┐
├─╴ banana\$
├─┐ a
│ ├─┐ na
│ │ ├─╴ na\$
│ │ └─╴ \$
│ └─╴ \$
├─┐ na
│ ├─╴ na\$
│ └─╴ \$
└─╴ \$
```

## Nim

Translation of: Go
```type

Tree = seq[Node]

Node = object
sub: string   # a substring of the input string.
ch: seq[int]  # list of child nodes.

proc addSuffix(t: var Tree; suf: string) =
var n, i = 0
while i < suf.len:
let b = suf[i]
let ch = t[n].ch
var x2, n2: int
while true:
if x2 == ch.len:
# No matching child, remainder of "suf" becomes new node.
n2 = t.len
return
n2 = ch[x2]
if t[n2].sub[0] == b: break
inc x2

# Find prefix of remaining suffix in common with child.
let sub2 = t[n2].sub
var j = 0
while j < sub2.len:
if suf[i+j] != sub2[j]:
# Split "sub2".
let n3 = n2
# New node for the part in common.
n2 = t.len
t[n3].sub = sub2[j..^1]   # Old node loses the part in common.
t[n].ch[x2] = n2
break   # Continue down the tree.
inc j
inc i, j  # Advance past part in common.
n = n2    # Continue down the tree.

func newTree(s: string): Tree =
for i in 0..s.high:

proc vis(t: Tree) =
if t.len == 0:
echo "<empty>"
return

proc f(n: int; pre: string) =
let children = t[n].ch
if children.len == 0:
echo "╴", t[n].sub
return
echo "┐", t[n].sub
for i in 0..<children.high:
stdout.write pre, "├─"
f(children[i], pre & "│ ")
stdout.write pre, "└─"
f(children[^1], pre & "  ")

f(0, "")

newTree("banana\$").vis()
```
Output:
```┐
├─╴banana\$
├─┐a
│ ├─┐na
│ │ ├─╴na\$
│ │ └─╴\$
│ └─╴\$
├─┐na
│ ├─╴na\$
│ └─╴\$
└─╴\$```

## Perl

Translation of: Raku
```use strict;
use warnings;
use Data::Dumper;

sub classify {
my \$h = {};
for (@_) { push @{\$h->{substr(\$_,0,1)}}, \$_ }
return \$h;
}
sub suffixes {
my \$str = shift;
map { substr \$str, \$_ } 0 .. length(\$str) - 1;
}
sub suffix_tree {
return +{} if @_ == 0;
return +{ \$_[0] => +{} } if @_ == 1;
my \$h = {};
my \$classif = classify @_;
for my \$key (keys %\$classif) {
my \$subtree = suffix_tree(
map { substr \$_, 1 } @{\$classif->{\$key}}
);
my @subkeys = keys %\$subtree;
if (@subkeys == 1) {
my (\$subkey) = @subkeys;
\$h->{"\$key\$subkey"} = \$subtree->{\$subkey};
} else { \$h->{\$key} = \$subtree }
}
return \$h;
}
print +Dumper suffix_tree suffixes 'banana\$';
```
Output:
```\$VAR1 = {
'\$' => {},
'a' => {
'\$' => {},
'na' => {
'na\$' => {},
'\$' => {}
}
},
'banana\$' => {},
'na' => {
'na\$' => {},
'\$' => {}
}
};```

## Phix

Translation of: D
```with javascript_semantics
-- tree nodes are simply {string substr, sequence children_idx}
enum SUB=1, CHILDREN=2

int n = 1, i = 1
while i<=length(suffix) do
integer ch = suffix[i], x2 = 1, n2
while (true) do
sequence children = t[n][CHILDREN]
if x2>length(children) then
-- no matching child, remainder of suffix becomes new node.
t = append(t,{suffix[i..\$],{}})
t[n][CHILDREN] = deep_copy(children)&length(t)
return t
end if
n2 = children[x2]
if t[n2][SUB][1]==ch then exit end if
x2 += 1
end while
-- find prefix of remaining suffix in common with child
string prefix = t[n2][SUB]
int j = 0
while j<length(prefix) do
if suffix[i+j]!=prefix[j+1] then
-- split n2: new node for the part in common
t = append(t,{prefix[1..j],{n2}})
-- old node loses the part in common
t[n2][SUB] = prefix[j+1..\$]
-- and child idx moves to newly created node
n2 = length(t)
sequence children = deep_copy(t[n][CHILDREN])
children[x2] = n2
t[n][CHILDREN] = children
exit    -- continue down the tree
end if
j += 1
end while
i += j  -- advance past part in common
n = n2  -- continue down the tree
end while
return t
end function

function SuffixTree(string s)
sequence t = {{"",{}}}
for i=1 to length(s) do
end for
return t
end function

procedure visualize(sequence t, integer n=1, string pre="")
if length(t)=0 then
printf(1,"<empty>\n");
return;
end if
sequence children = t[n][CHILDREN]
if length(children)=0 then
printf(1,"- %s\n", {t[n][SUB]})
return
end if
printf(1,"+ %s\n", {t[n][SUB]})
integer l = length(children)
for i=1 to l do
puts(1,pre&"+-")
visualize(t,children[i],pre&iff(i=l?"  ":"| "))
end for
end procedure

sequence t = SuffixTree("banana\$")
visualize(t)
```
Output:
```+
+-- banana\$
+-+ a
| +-+ na
| | +-- na\$
| | +-- \$
| +-- \$
+-+ na
| +-- na\$
| +-- \$
+-- \$
```

## Python

Translation of: D
```class Node:
def __init__(self, sub="", children=None):
self.sub = sub
self.ch = children or []

class SuffixTree:
def __init__(self, str):
self.nodes = [Node()]
for i in range(len(str)):

n = 0
i = 0
while i < len(suf):
b = suf[i]
x2 = 0
while True:
children = self.nodes[n].ch
if x2 == len(children):
# no matching child, remainder of suf becomes new node
n2 = len(self.nodes)
self.nodes.append(Node(suf[i:], []))
self.nodes[n].ch.append(n2)
return
n2 = children[x2]
if self.nodes[n2].sub[0] == b:
break
x2 = x2 + 1

# find prefix of remaining suffix in common with child
sub2 = self.nodes[n2].sub
j = 0
while j < len(sub2):
if suf[i + j] != sub2[j]:
# split n2
n3 = n2
# new node for the part in common
n2 = len(self.nodes)
self.nodes.append(Node(sub2[:j], [n3]))
self.nodes[n3].sub = sub2[j:] # old node loses the part in common
self.nodes[n].ch[x2] = n2
break # continue down the tree
j = j + 1
i = i + j   # advance past part in common
n = n2      # continue down the tree

def visualize(self):
if len(self.nodes) == 0:
print "<empty>"
return

def f(n, pre):
children = self.nodes[n].ch
if len(children) == 0:
print "--", self.nodes[n].sub
return
print "+-", self.nodes[n].sub
for c in children[:-1]:
print pre, "+-",
f(c, pre + " | ")
print pre, "+-",
f(children[-1], pre + "  ")

f(0, "")

SuffixTree("banana\$").visualize()
```
Output:
```+-
+- -- banana\$
+- +- a
|  +- +- na
|  |  +- -- na\$
|  |  +- -- \$
|  +- -- \$
+- +- na
|  +- -- na\$
|  +- -- \$
+- -- \$```

## Racket

See Suffix trees with Ukkonen’s algorithm by Danny Yoo for more information on how to use suffix trees in Racket.

```#lang racket
(require (planet dyoo/suffixtree))
(define tree (make-tree))

(define (show-node nd dpth)
(define children (node-children nd))
(printf "~a~a ~a~%" (match dpth
[(regexp #px"(.*) \$" (list _ d)) (string-append d "`")]
[else else]) (if (null? children) "--" "-+") (label->string (node-up-label nd)))
(let l ((children children))
(match children
((list) (void))
((list c) (show-node c (string-append dpth "  ")))
((list c ct ...) (show-node c (string-append dpth " |")) (l ct)))))

(show-node (tree-root tree) "")
```
Output:
```-+
|-- \$
|-+ a
| |-- \$
| `-+ na
|   |-- \$
|   `-- na\$
|-+ na
| |-- \$
| `-- na\$
`-- banana\$```

## Raku

(formerly Perl 6)

Works with: Rakudo version 2018.04

Here is quite a naive algorithm, probably ${\displaystyle O(n^{2})}$.

The display code is a variant of the visualize a tree task code.

```multi suffix-tree(Str \$str) { suffix-tree flat map &flip, [\~] \$str.flip.comb }
multi suffix-tree(@a) {
hash
@a == 0 ?? () !!
@a == 1 ?? ( @a[0] => [] ) !!
gather for @a.classify(*.substr(0, 1)) {
my \$subtree = suffix-tree(grep *.chars, map *.substr(1), .value[]);
if \$subtree == 1 {
my \$pair = \$subtree.pick;
take .key ~ \$pair.key => \$pair.value;
} else {
take .key => \$subtree;
}
}
}

my \$tree = root => suffix-tree 'banana\$';

.say for visualize-tree \$tree, *.key, *.value.List;

sub visualize-tree(\$tree, &label, &children,
:\$indent = '',
:@mid = ('├─', '│ '),
:@end = ('└─', '  '),
) {
sub visit(\$node, *@pre) {
gather {
take @pre[0] ~ \$node.&label;
my @children = sort \$node.&children;
my \$end = @children.end;
for @children.kv -> \$_, \$child {
when \$end { take visit(\$child, (@pre[1] X~ @end)) }
default   { take visit(\$child, (@pre[1] X~ @mid)) }
}
}
}
flat visit(\$tree, \$indent xx 2);
}
```
Output:
```root
├─\$
├─a
│ ├─\$
│ └─na
│   ├─\$
│   └─na\$
├─banana\$
└─na
├─\$
└─na\$```

## Sidef

Translation of: Raku
```func suffix_tree(Str t) {
suffix_tree(^t.len -> map { t.substr(_) })
}

func suffix_tree(a {.len == 1}) {
Hash(a[0] => nil)
}

func suffix_tree(Arr a) {
var h = Hash()
for k,v in (a.group_by { .char(0) }) {
var subtree = suffix_tree(v.map { .substr(1) })
var subkeys = subtree.keys
if (subkeys.len == 1) {
var subk = subkeys[0]
h{k + subk} = subtree{subk}
}
else {
h{k} = subtree
}
}
return h
}

say suffix_tree('banana\$')
```
Output:
```Hash(
"\$" => nil,
"a" => Hash(
"\$" => nil,
"na" => Hash(
"\$" => nil,
"na\$" => nil
)
),
"banana\$" => nil,
"na" => Hash(
"\$" => nil,
"na\$" => nil
)
)
```

## Wren

Translation of: Kotlin
```class Node {
construct new() {
_sub = ""  // a substring of the input string
_ch  = []  // list of child nodes
}

sub { _sub }
ch  { _ch  }

sub=(s) { _sub = s }
}

class SuffixTree {
construct new(str) {
_nodes = [Node.new()]
}

var n = 0
var i = 0
while (i < suf.count) {
var b  = suf[i]
var children = _nodes[n].ch
var x2 = 0
var n2
while (true) {
if (x2 == children.count) {
// no matching child, remainder of suf becomes new node.
n2 = _nodes.count
var nd = Node.new()
nd.sub = suf[i..-1]
return
}
n2 = children[x2]
if (_nodes[n2].sub[0] == b) break
x2 = x2 + 1
}
// find prefix of remaining suffix in common with child
var sub2 = _nodes[n2].sub
var j = 0
while (j < sub2.count) {
if (suf[i + j] != sub2[j]) {
// split n2
var n3 = n2
// new node for the part in common
n2 = _nodes.count
var nd = Node.new()
nd.sub = sub2[0...j]
_nodes[n3].sub = sub2[j..-1]  // old node loses the part in common
_nodes[n].ch[x2] = n2
break  // continue down the tree
}
j = j + 1
}
i = i + j  // advance past part in common
n = n2     // continue down the tree
}
}

visualize() {
if (_nodes.isEmpty) {
System.print("<empty>")
return
}

var f // recursive closure
f = Fn.new { |n, pre|
var children = _nodes[n].ch
if (children.isEmpty) {
System.print("╴ %(_nodes[n].sub)")
return
}
System.print("┐ %(_nodes[n].sub)")
for (c in children[0...-1]) {
System.write(pre + "├─")
f.call(c, pre + "│ ")
}
System.write(pre + "└─")
f.call(children[-1], pre + "  ")
}

f.call(0, "")
}
}

SuffixTree.new("banana\$").visualize()
```
Output:
```┐
├─╴ banana\$
├─┐ a
│ ├─┐ na
│ │ ├─╴ na\$
│ │ └─╴ \$
│ └─╴ \$
├─┐ na
│ ├─╴ na\$
│ └─╴ \$
└─╴ \$
```