# LC283 - Move Zeroes
# 双指针

class Solution {
    
    public void moveZeroes(int[] nums) {
        // sanity check
        if (nums == null || nums.length == 0) {
            return;
        }
        
        int length = nums.length;
        // the elements from 0 to i but not include i are not 0
        int i = 0, j = 0;
        while (j < length) {
            if (nums[j] != 0) {
                swap(nums, i++, j);
            }
            j++;
        }
    }
    
    private void swap(int[] nums, int i, int j) {
        int temp = nums[i];
        nums[i] = nums[j];
        nums[j] = temp;
    }
}