Sorting algorithms/Insertion sort
An O(n^2) sorting algorithm which moves elements one at a time into the correct position. The algorithm is as follows (from the wikipedia):
You are encouraged to solve this task according to the task description, using any language you may know.
Sorting Algorithm
This is a sorting algorithm. It may be applied to a set of data in order to sort it.
For comparing various sorts, see compare sorts.
For other sorting algorithms, see sorting algorithms, or:
Heap sort | Merge sort | Patience sort | Quick sort
O(n log2n) sorts
Shell Sort
O(n2) sorts
Bubble sort |
Cocktail sort |
Cocktail sort with shifting bounds |
Comb sort |
Cycle sort |
Gnome sort |
Insertion sort |
Selection sort |
Strand sort
other sorts
Bead sort |
Bogo sort |
Common sorted list |
Composite structures sort |
Custom comparator sort |
Counting sort |
Disjoint sublist sort |
External sort |
Jort sort |
Lexicographical sort |
Natural sorting |
Order by pair comparisons |
Order disjoint list items |
Order two numerical lists |
Object identifier (OID) sort |
Pancake sort |
Quickselect |
Permutation sort |
Radix sort |
Ranking methods |
Remove duplicate elements |
Sleep sort |
Stooge sort |
[Sort letters of a string] |
Three variable sort |
Topological sort |
Tree sort
insertionSort(array A) for i = 1 to length[A]-1 do value = A[i] j = i-1 while j >= 0 and A[j] > value do A[j + 1] = A[j] j = j-1 A[j+1] = value
Writing the algorithm for integers will suffice.
Common Lisp
(defun span (predicate list) (let ((tail (member-if-not predicate list))) (values (ldiff list tail) tail))) (defun less-than (x) (lambda (y) (< y x))) (defun insert (list elt) (multiple-value-bind (left right) (span (less-than elt) list) (append left (list elt) right))) (defun insertion-sort (list) (reduce #'insert list :initial-value nil))
D
import std.stdio: writefln; void insertionSort(T)(T[] A) { for(int i = 1; i < A.length; i++) { T value = A[i]; int j = i - 1; while (j >= 0 && A[j] > value) { A[j + 1] = A[j]; j = j - 1; } A[j+1] = value; } } void main() { auto a1 = [4, 65, 2, -31, 0, 99, 2, 83, 782, 1]; insertionSort(a1); writefln(a1); auto a2 = [4.0,65.0,2.0,-31.0,0.0,99.0,2.0,83.0,782.0,1.0]; insertionSort(a2); writefln(a2); }
Haskell
insert x [] = [x] insert x (y:ys) | x <= y = x:y:ys insert x (y:ys) | otherwise = y:(insert x ys) insertionSort :: Ord a => [a] -> [a] insertionSort = foldr insert [] -- Example use: -- *Main> insertionSort [6,8,5,9,3,2,1,4,7] -- [1,2,3,4,5,6,7,8,9]
Java
public static void insertSort(int[] A){ for(int i = 1; i < A.length; i++){ int value = A[i]; int j = i - 1; while(j >= 0 && A[j] > value){ A[j + 1] = A[j]; j = j - 1; } A[j + 1] = value; } }
Python
def insertion_sort(l): for i in xrange(1, len(l)): j = i-1 key = l[i] while (l[j] > key) and (j >= 0): l[j+1] = l[j] j -= 1 l[j+1] = key
Insertion sort with binary search
def insertion_sort_bin(seq): for i in range(1, len(seq)): key = seq[i] # invariant: ``seq[:i]`` is sorted # find the least `low' such that ``seq[low]`` is not less then `key'. # Binary search in sorted sequence ``seq[low:up]``: low, up = 0, i while up > low: middle = (low + up) // 2 if seq[middle] < key: low = middle + 1 else: up = middle # insert key at position ``low`` seq[:] = seq[:low] + [key] + seq[low:i] + seq[i + 1:]