Sort an array which contain 1 to n values

You have given an array which contain 1 to n element, your task is to sort this array in an efficient way and without replace with 1 to n numbers.

Examples :

Input : arr[] = {10, 7, 9, 2, 8, 
                 3, 5, 4, 6, 1};
Output : 1 2 3 4 5 6 7 8 9 10

Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Native approach :
Sort this array with the use of any type of sorting method. it takes O(nlogn) minimum time.

Efficient approach :
Replace every element with it’s position. it takes O(n) efficient time and give you the sorted array. Let’s understand this approach with the code below.

C++

// Efficient C++ program to sort an array of
// numbers in range from 1 to n.
#include <iostream>
using namespace std;

// function for sort array
void sortit(int arr[], int n)
{
    for (int i = 0; i < n; i++) {

        // replace this element with it's position
        // while element not get the position
        // swap this element to it's position
        while (i != (arr[i] - 1)) 
            swap(arr[i], arr[arr[i] - 1]);        
    }
}

// Driver code
int main()
{
    int arr[] = { 10, 7, 9, 2, 8, 3, 5, 4, 6, 1 };
    int n = sizeof(arr) / sizeof(arr[0]);

    // for sort an array
    sortit(arr, n);

    // for print all the element in sorted way
    for (int i = 0; i < n; i++) 
        cout << arr[i] << " ";    
}

Java

// Efficient Java program to sort an 
// array of numbers in range from 1
// to n.
import java.io.*;
import java.util.*;

public class GFG {
    
    //swap function
    public static int swap(int itself,
                            int dummy)
    {
        return itself;
    }
    
    // function for sort array
    static void sortit(int []arr, int n)
    {
        for (int i = 0; i < n; i++) 
        {
    
            // replace this element with
            // it's position while element
            // not get the position swap 
            // this element to it's position
            while (i != (arr[i] - 1)) 
                arr[i] = swap(arr[arr[i] - 1],
                    arr[arr[i] - 1] = arr[i]);     
        }
    }
    
    // Driver code
    public static void main(String args[])
    {
        int []arr = {10, 7, 9, 2, 8, 
                              3, 5, 4, 6, 1};
        int n = arr.length;
    
        // for sort an array
        sortit(arr, n);
    
        // for print all the 
        // element in sorted way
        for (int i = 0; i < n; i++) 
            System.out.print(arr[i] + " "); 
    }
}

// This code is contributed by Manish Shaw 
// (manishshaw1)

C#

// Efficient C# program to sort an array of
// numbers in range from 1 to n.
using System;
using System.Collections.Generic;

class GFG {
    
    //swap function
    static void swap(ref int a, ref int b)
    {
        int value = a;
        a = b;
        b = value;
    }
    
    // function for sort array
    static void sortit(int []arr, int n)
    {
        for (int i = 0; i < n; i++) 
        {
    
            // replace this element with it's position
            // while element not get the position
            // swap this element to it's position
            while (i != (arr[i] - 1)) 
                swap(ref arr[i], ref arr[arr[i] - 1]);     
        }
    }
    
    // Driver code
    public static void Main()
    {
        int []arr = {10, 7, 9, 2, 8, 
                      3, 5, 4, 6, 1};
        int n = arr.Length;
    
        // for sort an array
        sortit(arr, n);
    
        // for print all the 
        // element in sorted way
        for (int i = 0; i < n; i++) 
            Console.Write(arr[i] + " "); 
    }
}

// This code is contributed by 
// Manish Shaw (manishshaw1)

PHP

<?php
// Efficient PHP program to sort an 
// array of numbers in range from 1 to n.

function swap(&$x, &$y)
{
    $x ^= $y ^= $x ^= $y;
}

// function for sort array
function sortit(&$arr, $n)
{
    for ($i = 0; $i < $n; $i++) 
    {

        // replace this element with 
        // it's position while element 
        // not get the position
        // swap this element to it's position
        while ($i != ($arr[$i] - 1)) 
            swap($arr[$i], $arr[$arr[$i] - 1]);     
    }
}

// Driver code
$arr = array(10, 7, 9, 2, 8, 
             3, 5, 4, 6, 1);
$n = count($arr);

// for sort an array
sortit($arr, $n);

// for print all the
// element in sorted way
for ($i = 0; $i < $n; $i++) 
    echo $arr[$i]." ";

//This code is contributed by Manish Shaw
//(manishshaw1)
?>

Output :

1 2 3 4 5 6 7 8 9 10

My Personal Notes

DevanshuAgarwal

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Improved By : manishshaw1

Practice Tags :

Arrays

Sorting