SwapAlternate.java

// Swap Alternate 

// You have been given an array/list(ARR)of size N.You need to swap every pair of alternate elements in the array/list.
// You don'tneed to print or return anything,just change in the input array itself.

// Input Format:The first line contains an Integer't'which denotes the number of test cases or queries to be run.Then the test cases follow.

// First line of each test case or query contains an integer'N'representing the size of the array/list.

// Second line contains'N'single space separated integers representing the elements in the array/list.

// Output Format:
// For each test case,print the elements of the resulting array in a single row separated by a single space.

// Output for every test case will be printed in a separate line.

// Constraints:
// 1<=t<=10^2 
// 0<=N<=10^5 
// Time Limit:1 sec 

// Sample Input 1:
// 1 
// 6 9 3 6 12 4 32 
// Sample Output 1:
// 3 9 12 6 32 4 

// Sample Input 2:
// 2 
// 9 
// 9 3 6 12 4 32 5 11 19 
// 4 
// 1 2 3 4 
// Sample Output 2:
// 3 9 12 6 32 4 11 5 19 
// 2 1 4 3


packageArray;
importjava.util.Scanner;

publicclassSwapAlternate {
publicstaticvoidprintArray(int[] arr1) {
intn = arr1.length;
for (inti = 0; i < n; i++) {
System.out.print(arr1[i]);
 }
 }

publicstaticint[] swapAlternate(int[] arr) {
intn = arr.length;
for (inti = 0; i < n - 1; i += 2) {
inttemp = arr[i];
arr[i] = arr[i + 1];
arr[i + 1] = temp;
 }
returnarr;
 }

publicstaticint[] takingInput() {
Scannersc = newScanner(System.in);
intn = sc.nextInt();
int[] arr = newint[n];
for (inti = 0; i < n; i++) {
arr[i] = sc.nextInt();
 }
returnarr;
 }

publicstaticvoidmain(String[] args) {
int[] arr = takingInput();
int[] arr1 = swapAlternate(arr);
printArray(arr1);
 }
}