Shuffle the position of each Array element by swapping adjacent elements
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:
- If length of the array is even then we can easily Swap 2 Variables without using 3rd variable for every pair of contiguous elements.
- If length of array is odd then we can do the same as above but the the last 3 elements will not form a pair, So will we can easily Swap those 3 Variables without using 4th variable.
Below is the implementation of the above approach:
C++
// 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
// 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
# 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#
// 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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