# Sort an almost sorted array where only two elements are swapped

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Vinay Khatri
Last updated on June 14, 2024

## Problem

How can an almost-sorted array with only two members swapped be effectively sorted?

#### Sample Input

`[1, 5, 3]`

#### Sample Output

`[1, 3, 5]`

#### Explanation

`3 and 5 got swapped`

### Approach

The goal is to go from right to left and discover the first out-of-order number (a number that is smaller than the previous number). Once the first number is located, traverse the array toward the left side to find the other out-of-order element. The approach takes O(N) time.

### C++ Programming

```#include<iostream>
#include<algorithm>
using namespace std;

//function to sort an array
void sortArray(int arr[], int n)
{
// Traverse the given array from right side
for (int i = n-1; i > 0; i--)
{
// if arr[i] is not in order
if (arr[i] < arr[i-1])
{
int j = i-1;
while (j>=0 && arr[i] < arr[j])
j--;
swap(arr[i], arr[j+1]);
break;
}
}
}
int main()
{
int arr[] = {1, 5, 3};
int n = sizeof(arr)/sizeof(arr[0]);

sortArray(arr, n);

for(int i=0;i<n;i++) cout<<arr[i]<<" ";
return 0;
}
```

Output

`1 3 5`

### C Programming

```#include<stdio.h>

//function to sort an array
void sortArray(int arr[], int n)
{
// Traverse the given array from right side
for (int i = n-1; i > 0; i--)
{
// if arr[i] is not in order
if (arr[i] < arr[i-1])
{
int j = i-1;
while (j>=0 && arr[i] < arr[j])
j--;
int temp = arr[i];  //swap the elements
arr[i] = arr[j+1];
arr[j+1] = temp;
break;
}
}
}
void main()
{
int arr[] = {1, 5, 3};
int n = sizeof(arr)/sizeof(arr[0]);

sortArray(arr, n);
for(int i=0;i<n;i++) printf("%d ",arr[i]);
}```

Output

`1 3 5`

### Java Programming

```import java.io.*;

class Solution
{
//function to sort
static void sortArray(int arr[], int n)
{
// Traverse the given array
// from right side
for (int i = n - 1; i > 0; i--)
{
// if arr[i]
// is not in order
if (arr[i] < arr[i - 1])
{
// find the other element
// to be swapped with arr[i]
int j = i - 1;
while (j >= 0 && arr[i] < arr[j])
j--;
// Swap
int temp = arr[i];
arr[i] = arr[j + 1];
arr[j + 1] = temp;

break;
}
}
}

public static void main(String[] args)
{
int arr[] = {1, 5, 3};
int n = arr.length;

sortArray(arr, n);

for (int i = 0; i < n; i++)
System.out.print(arr[i] + " ");
System.out.println();
}
}```

Output

`1 3 5`

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