Move Zeroes

Given an array nums, write a function to move all 0's to the end of it while maintaining the relative order of the non-zero elements.>

For example, given nums = [0, 1, 0, 3, 12], after calling your function, nums should be [1, 3, 12, 0, 0].

Note: You must do this in-place without making a copy of the array. Minimize the total number of operations.

把所有零移动到最后，要求in-place不能额外开辟新的数组。

这道题思路上有点像Remove Element，用两个指针，一个往后移动发现非零的元素就与另一个指针交换元素。注意交换之要判断两个指针是否指向同一个元素以避免死循环。

public void moveZeroes(int[] nums) {
    int j = 0;
    for (int i = 0; i < nums.length; i++) {
        if (nums[i] != 0) {
            if (i > j) {
                nums[j] = nums[i];
                nums[i] = 0;
            }
            j++;
        }
    }
}