Move Zeroes to the front of an Integer Array

Given an array of integers, move all the zeroes to the beginning of the array, leaving the order of the other integers unaltered. This operation has to be done in place.

Time Complexity O(n)
Java

package algos;

public class moveZeroesToStart {

	public static int[] moveToStart(int[] input) {
		int n = input.length - 1, count = n-1;
		for (int i = n - 1; i >= 0; i--) {
			if (input[i] != 0) {
				input[count--] = input[i];
			}
		}

		while (count >= 0) {
			input[count--] = 0;
		}

		return input;
	}

	public static int[] moveToEnd(int[] input) {
		int n = input.length, count = 0;
		for (int i = 0; i < n; i++) {
			if (input[i] != 0) {
				input[count++] = input[i];
			}
		}

		while (count < n) {
			input[count++] = 0;
		}

		return input;
	}

	public static void main(String[] args) {

		int[] arr = { 3, 2, 0, 1, 5, 0, 0 };
		arr = moveToStart(arr);
		for (int i = 0; i < arr.length; i++) {
			System.out.println(arr[i]);
		}
                System.out.println();
		arr = moveToEnd(arr);
		for (int i = 0; i < arr.length; i++) {
			System.out.println(arr[i]);
		}
	}
}

Output

JavaScript

var moveToStart = function(input) {
  var n = input.length - 1;
  var count = n-1;
  for (var i = n - 1; i >= 0; i--) {
    if (input[i] !== 0) {
      input[count--] = input[i];
    }
  }
  while (count >= 0) {
    input[count--] = 0;
  };
  return input;
};

var moveToEnd = function(input) {
  var n = input.length;
  var count = 0;
  for (var i = 0; i < n; i++) {
    if (input[i] !== 0) {
      input[count++] = input[i];
    }
  }
  while (count < n) {
    input[count++] = 0;
  };
  return input;
};

var arr = [3, 2, 0, 1, 5, 0, 0];
arr = moveToStart(arr);
for (var i = 0; i < arr.length; i++) {
  console.info(arr[i]);
}
console.log();
arr = moveToEnd(arr);
for (var i = 0; i < arr.length; i++) {
  console.info(arr[i]);
}

Demo

Follow Up
To do the opposite and move zeroes to the end of the array we need to start from the beginning with the counter at 0.

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