Day 32 - Search and Sort Algorithms Part E: Selection Sort

Source: GeeksForGeeks

The selection sort algorithm sorts an array by repeatedly finding the minimum element (considering ascending order) from unsorted part and putting it at the beginning. The algorithm maintains two subarrays in a given array.

1. The subarray which is already sorted
2. Remaining subarray which is unsorted

In every iteration of selection sort, the minimum element (considering ascending order) from the unsorted subarray is picked and moved to the sorted subarray

Question

Given an unsorted list of elements, write a program to sort the given list using selection sort.

Example

input: [1, 5, 2, 7, 3, 4, 8, 9, 6]
output: [1, 2, 3, 4, 5, 6, 7, 8, 9]

Solution

JavaScript Implementation

function selectionSort(arr){
    for(var i = 0; i < arr.length; i++){
        var lowest = i;
        for(var j = i+1; j < arr.length; j++){
            if(arr[j] < arr[lowest]){
                lowest = j;
            }
        }
        if(i !== lowest){
            var temp = arr[i];
            arr[i] = arr[lowest];
            arr[lowest] = temp;
        }
    }
    return arr;
}

console.log ( selectionSort ([1, 5, 2, 7, 3, 4, 8, 9, 6]));

C++ Implementation

/*
* @author : imkaka
* @date   : 2/1/2019
*
*/

#include<iostream>

using namespace std;

void selectionSort(int arr[], int size){

    for(int i = 0; i < size; ++i){
        for(int j = i+1; j < size; ++j){
            if(arr[i] > arr[j]){
                int temp = arr[i];
                arr[i] = arr[j];
                arr[j] = temp;
            }
        }
    }
}

void print(int arr[], int size){
    for(int x = 0; x < size; ++x){
        cout << arr[x] << " ";
    }
    cout << endl;
}
int main(){

    int arr[] = {20, 46, 2, 43, 10, -29, 10, 0, 12};
    int size = sizeof(arr)/sizeof(arr[0]);
    cout << "Before Sorting " << endl;
    print(arr, size);

    selectionSort(arr, size);

    cout << endl;
    cout << "After Sorting " << endl;
    print(arr, size);

    return 0;
}

Java Implementation

Solution

/**
 * @date 01/02/19
 * @author SPREEHA DUTTA
 */
import java.util.*;
public class selectionSort {
    public static void main(String []args)
    {
        int n,i,j,t,min=0;
        Scanner sc=new Scanner(System.in);
        n=sc.nextInt();
        int arr[]=new int[n];
        for(i=0;i<n;i++)
            arr[i]=sc.nextInt();
        for(i=0;i<n;i++)
        {
            min=i;
            for(j=i;j<n;j++)
            {
                if(arr[min]>arr[j])
                    min=j;
            }
            t=arr[i];
            arr[i]=arr[min];
            arr[min]=t;
        }
        System.out.println("The sorted array is: ");
        for(i=0;i<n;i++)
            System.out.print(arr[i]+" ");
    }
}