PushZeroesToEnd.java

// Push Zeros to end
// Send Feedback
// You have been given a random integer array/list(ARR) of size N. You have been required to push all the zeros that are present in the array/list to the end of it. Also, make sure to maintain the relative order of the non-zero elements.
// Note:
// Change in the input array/list itself. You don't need to return or print the elements.

// You need to do this in one scan of array only. Don't use extra space.

// 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 array/list in the desired order 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
// 7
// 2 0 0 1 3 0 0
// Sample Output 1:
// 2 1 3 0 0 0 0
//  Explanation for the Sample Input 1 :
// All the zeros have been pushed towards the end of the array/list. Another important fact is that the order of the non-zero elements have been maintained as they appear in the input array/list.
// Sample Input 2:
// 2
// 5
// 0 3 0 2 0
// 5
// 9 0 0 8 2
// Sample Output 2:
// 3 2 0 0 0
// 9 8 2 0 0 

import java.util.Scanner;

public class PushZeroesToEnd {

    public static void takeInput(int arr[], int n, Scanner s) {
        System.out.println("Enter Values Of The Array : ");
        for (int i = 0; i < n; i++) {
            arr[i] = s.nextInt();
        }
    }

    public static void printArray(int arr[], int N) {
        System.out.println("Output : ");
        for (int i = 0; i < N; i++) {
            System.out.print(arr[i] + " ");
        }
        System.out.println();
    }

    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        System.out.println("Enter number of test cases: ");
        int t = s.nextInt();
        for (int i = 1; i <= t; i++) {
            System.out.println("Enter Length Of " + i + "th test case 1st Array");
            int N = s.nextInt();
            int arr[] = new int[N];
            takeInput(arr, N, s);
            PushZeroesAtEnd(arr, N);
            printArray(arr, N);

        }
    }

    public static void PushZeroesAtEnd(int arr[], int N) {

        int countNonZero = 0;
        for(int i=0;i<N;i++)
        {
            if(arr[i]!=0)
            {
                arr[countNonZero] = arr[i];
                countNonZero++;
            }
        }

        for(int j=countNonZero;j<N;j++)
        {
            arr[j]=0;
        }
    }
}