Last list item

From Rosetta Code
Revision as of 09:13, 23 October 2021 by PureFox (talk | contribs) (→‎{{header|Go}}: Updated in line with Wren.)
Last list item 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.
Task

List = [6, 81, 243, 14, 25, 49, 123, 69, 11]
Find two smallest items, summarize them, add to the end of list and delete them.
Repeat it until list contains one element.
Show the steps and last item on this page.

C

Translation of: Wren

<lang c>#include <stdio.h>

  1. include <stdlib.h>

int compare(const void *a, const void *b) {

   int aa = *(const int *)a;
   int bb = *(const int *)b;
   if (aa < bb) return -1;
   if (aa > bb) return 1;
   return 0;

}

int main() {

   int a[] = {6, 81, 243, 14, 25, 49, 123, 69, 11};
   int isize = sizeof(int);
   int asize = sizeof(a) / isize;
   int i, sum;
   while (asize > 1) {
       qsort(a, asize, isize, compare);
       sum = a[0] + a[1];
       for (i = 2; i < asize; ++i) a[i-2] = a[i];
       a[asize - 2] = sum;
       asize--;
   }
   printf("Last item is %d.\n", a[0]);
   return 0;

}</lang>

Output:
Last item is 621.

Go

Translation of: Wren

<lang go>package main

import (

   "fmt"
   "sort"

)

func main() {

   a := []int{6, 81, 243, 14, 25, 49, 123, 69, 11}
   for len(a) > 1 {
       sort.Ints(a)
       fmt.Println("Sorted list:", a)
       sum := a[0] + a[1]
       fmt.Printf("Two smallest: %d + %d = %d\n", a[0], a[1], sum)
       a = append(a, a[0]+a[1])
       a = a[2:]
   }
   fmt.Println("Last item is", a[0], "\b.")

}</lang>

Output:
Sorted list: [6 11 14 25 49 69 81 123 243]
Two smallest: 6 + 11 = 17
Sorted list: [14 17 25 49 69 81 123 243]
Two smallest: 14 + 17 = 31
Sorted list: [25 31 49 69 81 123 243]
Two smallest: 25 + 31 = 56
Sorted list: [49 56 69 81 123 243]
Two smallest: 49 + 56 = 105
Sorted list: [69 81 105 123 243]
Two smallest: 69 + 81 = 150
Sorted list: [105 123 150 243]
Two smallest: 105 + 123 = 228
Sorted list: [150 228 243]
Two smallest: 150 + 228 = 378
Sorted list: [243 378]
Two smallest: 243 + 378 = 621
Last item is 621.

Ring

<lang ring> see "working..." + nl

List = [6,81,243,14,25,49,123,69,11] Temp = []

while true

     Temp = sort(List)
     first = Temp[1]
     second = Temp[2]
     ind1 = find(List,first)
     ind2 = find(List,second)
     if ind1 < ind2
        del(List,ind2)
        del(List,ind1)
     else
        del(List,ind1)
        del(List,ind2)
     ok
     sum = first + second 
     add(List,sum)
     if len(List) = 1
        exit
     ok
     showList(first,second,List)

end

see "Last item is: " +List[1] + nl see "done..." + nl

func showList(first,second,List)

    see "two smallest number is = " + first + " " + second + nl
    see "List = "
    showArray(List)     

func showArray(array)

    txt = ""
    see "["
    for n = 1 to len(array)
        txt = txt + array[n] + ","
    next
    txt = left(txt,len(txt)-1)
    txt = txt + "]"
    see txt + nl

</lang>

Output:
working...
two smallest number is = 6 11
List = [81,243,14,25,49,123,69,17]
two smallest number is = 14 17
List = [81,243,25,49,123,69,31]
two smallest number is = 25 31
List = [81,243,49,123,69,56]
two smallest number is = 49 56
List = [81,243,123,69,105]
two smallest number is = 69 81
List = [243,123,105,150]
two smallest number is = 105 123
List = [243,150,228]
two smallest number is = 150 228
List = [243,378]
Last item is: 621
done...

Wren

<lang ecmascript>var a = [6, 81, 243, 14, 25, 49, 123, 69, 11]

while (a.count > 1) {

   a.sort()
   System.print("Sorted list: %(a)")
   var sum = a[0] + a[1]
   System.print("Two smallest: %(a[0]) + %(a[1]) = %(sum)")
   a.add(sum)
   a = a[2..-1]

}

System.print("Last item is %(a[0]).")</lang>

Output:
Sorted list: [6, 11, 14, 25, 49, 69, 81, 123, 243]
Two smallest: 6 + 11 = 17
Sorted list: [14, 17, 25, 49, 69, 81, 123, 243]
Two smallest: 14 + 17 = 31
Sorted list: [25, 31, 49, 69, 81, 123, 243]
Two smallest: 25 + 31 = 56
Sorted list: [49, 56, 69, 81, 123, 243]
Two smallest: 49 + 56 = 105
Sorted list: [69, 81, 105, 123, 243]
Two smallest: 69 + 81 = 150
Sorted list: [105, 123, 150, 243]
Two smallest: 105 + 123 = 228
Sorted list: [150, 228, 243]
Two smallest: 150 + 228 = 378
Sorted list: [243, 378]
Two smallest: 243 + 378 = 621
Last item is 621.