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Shuffle the position of each Array element by swapping adjacent elements
  • Difficulty Level : Basic
  • Last Updated : 25 Aug, 2020

Given an array arr[], the task is to rearrange the array elements by swapping adjacent elements such that no element remains at same position after swapping.

Examples:

Input: arr[] = { 1, 2, 3, 4, 5 } 
Output: 2 1 5 3 4 
Explanation: 
Adjacent elements are swapped as follows: 
(1, 2 -> 2, 1) 
(3, 4, 5 -> 5, 3, 4)

Input: arr[] = {1, 2, 3, 4} 
Output: 2 1 4 3 
Explanation: 
Adjacent elements are swapped as follows: 
1, 2 -> 2, 1 
3, 4 -> 4, 3

Approach: The key observation in the problem is that there can be two cases for the arrays to swap the array elements:



Below is the implementation of the above approach:

C++

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// C++ program for the above approach 
#include <bits/stdc++.h> 
using namespace std; 
  
// Function to print the array 
void print(int a[], int n) 
    // Loop to iterate over the 
    // elements of array 
    for (int i = 0; i < n; i++) 
        cout << a[i] << " "
  
// Function to swap two variables without 
// using the third variable 
void swapTwo(int& x, int& y) 
    // Store XOR of all in x 
    x = x ^ y; 
  
    // After this, y has value of x 
    y = x ^ y; 
  
    // After this, x has value of y 
    x = x ^ y; 
  
// Function to swap three variables 
// without using fourth variable 
void swapThree(int& a, int& b, int& c) 
    // Store XOR of all in a 
    a = a ^ b ^ c; 
  
    // After this, b has value of a 
    b = a ^ b ^ c; 
  
    // After this, c has value of b 
    c = a ^ b ^ c; 
  
    // After this, a has value of c 
    a = a ^ b ^ c; 
  
// Function that swaps n integers 
void rearrangeArray(int a[], int n) 
    if (n % 2 == 0) { 
  
        for (int i = 0; i < n - 1; i += 2) { 
            // Swap 2 variables without 
            // using 3rd variable 
            swapTwo(a[i], a[i + 1]); 
        
    
    else
        for (int i = 0; i < n - 3; i += 2) { 
            // Swap 2 variables without 
            // using 3rd variable 
            swapTwo(a[i], a[i + 1]); 
        
  
        // The last 3 elements will not form 
        // pair if n is odd 
        // Hence, swapp 3 variables without 
        // using 4th variable 
        swapThree(a[n - 1], a[n - 2], a[n - 3]); 
    
  
    // Print the array elements 
    print(a, n); 
  
// Driver Code 
int main() 
    // Given array arr[] 
    int arr[] = { 1, 2, 3, 4, 5 }; 
    int n = sizeof(arr) / sizeof(arr[0]); 
  
    // Function Call 
    rearrangeArray(arr, n); 
    return 0; 

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Java

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// Java program for the above approach 
import java.util.*;
import java.lang.*;
  
class GFG{
      
// Function to print the array 
static void print(int a[], int n) 
      
    // Loop to iterate over the 
    // elements of array 
    for(int i = 0; i < n; i++) 
        System.out.print(a[i] + " "); 
  
// Function to swap two variables without 
// using the third variable 
static void swapTwo(int x, int y, int[] a) 
      
    // Store XOR of all in x 
    a[x] = a[x] ^ a[y]; 
  
    // After this, y has value of x 
    a[y] = a[x] ^ a[y]; 
  
    // After this, x has value of y 
    a[x] = a[x] ^ a[y]; 
  
// Function to swap three variables 
// without using fourth variable 
static void swapThree(int x, int y,
                      int z, int[] a) 
      
    // Store XOR of all in a 
    a[x] = a[x] ^ a[y] ^ a[z]; 
  
    // After this, b has value of a 
    a[y] = a[x] ^ a[y] ^ a[z]; 
  
    // After this, c has value of b 
    a[z] = a[x] ^ a[y] ^ a[z]; 
  
    // After this, a has value of c 
    a[x] = a[x] ^ a[y] ^ a[z]; 
  
// Function that swaps n integers 
static void rearrangeArray(int a[], int n) 
    if (n % 2 == 0
    
        for(int i = 0; i < n - 1; i += 2)
        {
              
            // Swap 2 variables without 
            // using 3rd variable 
            swapTwo(i, i + 1, a); 
        
    
    else 
    
        for(int i = 0; i < n - 3; i += 2
        {
              
            // Swap 2 variables without 
            // using 3rd variable 
            swapTwo(i, i + 1, a); 
        
  
        // The last 3 elements will not form 
        // pair if n is odd 
        // Hence, swapp 3 variables without 
        // using 4th variable 
        swapThree(n - 1, n - 2, n - 3, a); 
    
  
    // Print the array elements 
    print(a, n); 
      
// Driver code
public static void main (String[] args)
{
      
    // Given array arr[] 
    int arr[] = { 1, 2, 3, 4, 5 }; 
    int n = arr.length; 
      
    // Function call 
    rearrangeArray(arr, n);     
}
}
  
// This code is contributed by offbeat

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Python3

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# Python3 program for the above approach 
  
# Function to print the array 
def print1(a, n):
  
    # Loop to iterate over the 
    # elements of array 
    for i in range(n):
        print(a[i], end = " ")
  
# Function to swap two variables without 
# using the third variable 
def swapTwo(x, y):
  
    # Store XOR of all in x 
    x = x ^ y
  
    # After this, y has value of x 
    y = x ^ y
  
    # After this, x has value of y 
    x = x ^ y 
      
    return x, y
  
# Function to swap three variables 
# without using fourth variable 
def swapThree(a, b, c):
  
    # Store XOR of all in a 
    a = a ^ b ^ c
  
    # After this, b has value of a 
    b = a ^ b ^ c
  
    # After this, c has value of b 
    c = a ^ b ^ c
  
    # After this, a has value of c 
    a = a ^ b ^ c
  
    return a , b , c
  
# Function that swaps n integers 
def rearrangeArray(a, n):
  
    if (n % 2 == 0):
        for i in range (0, n - 1, 2):
              
            # Swap 2 variables without 
            # using 3rd variable 
            a[i], a[i + 1] = swapTwo(a[i], a[i + 1])
          
    else:
        for i in range(0, n - 3, 2):
              
            # Swap 2 variables without 
            # using 3rd variable 
            a[i], a[i + 1] = swapTwo(a[i], a[i + 1])
  
        # The last 3 elements will not form 
        # pair if n is odd 
        # Hence, swapp 3 variables without 
        # using 4th variable 
        a[n - 1], a[n - 2], a[n - 3] = swapThree(a[n - 1],
                                                 a[n - 2],
                                                 a[n - 3])
  
    # Print the array elements 
    print1(a, n)
  
# Driver Code 
if __name__ == "__main__":
  
    # Given array arr[] 
    arr = [1, 2, 3, 4, 5 ]
    n = len(arr)
  
    # Function call 
    rearrangeArray(arr, n)
  
# This code is contributed by chitranayal

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C#

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// C# program for the above approach
using System;
  
class GFG{
  
// Function to print the array
static void print(int []a, int n)
{
      
    // Loop to iterate over the
    // elements of array
    for(int i = 0; i < n; i++)
        Console.Write(a[i] + " ");
}
  
// Function to swap two variables without
// using the third variable
static void swapTwo(ref int x, ref int y)
{
      
    // Store XOR of all in x
    x = x ^ y;
  
    // After this, y has value of x
    y = x ^ y;
  
    // After this, x has value of y
    x = x ^ y;
}
  
// Function to swap three variables
// without using fourth variable
static void swapThree(ref int a, ref int b, 
                      ref int c)
{
      
    // Store XOR of all in a
    a = a ^ b ^ c;
  
    // After this, b has value of a
    b = a ^ b ^ c;
  
    // After this, c has value of b
    c = a ^ b ^ c;
  
    // After this, a has value of c
    a = a ^ b ^ c;
}
  
// Function that swaps n integers
static void rearrangeArray(int []a, int n)
{
    if (n % 2 == 0)
    {
        for(int i = 0; i < n - 1; i += 2) 
        {
              
            // Swap 2 variables without
            // using 3rd variable
            swapTwo(ref a[i], ref a[i + 1]);
        }
    }
    else
    {
        for(int i = 0; i < n - 3; i += 2) 
        {
              
            // Swap 2 variables without
            // using 3rd variable
            swapTwo(ref a[i], ref a[i + 1]);
        }
  
        // The last 3 elements will not form
        // pair if n is odd
        // Hence, swapp 3 variables without
        // using 4th variable
        swapThree(ref a[n - 1], ref a[n - 2], 
                  ref a[n - 3]);
    }
  
    // Print the array elements
    print(a, n);
}
  
// Driver Code
public static void Main(string []s)
{
      
    // Given array arr[]
    int []arr = { 1, 2, 3, 4, 5 };
    int n = arr.Length;
  
    // Function call
    rearrangeArray(arr, n);
}
}
  
// This code is contributed by rutvik_56

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Output: 

2 1 4 5 3

Time Complexity: O(N) 
Auxiliary Space: O(1)
 

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