Move Zeroes

题目

Given an arraynums, write a function to move all0's to the end of it while maintaining the relative order of the non-zero elements.

For example, givennums = [0, 1, 0, 3, 12], after calling your function,numsshould be[1, 3, 12, 0, 0].

Note:

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

分析

1. two pointers: fast, slow

2. fast pointer to traverse array, while slow pointer stops at index beginning at 0

3. once fast pointer encounters non-zero, assign this value to the item of slow pointer

4. increment slow pointer

5. fill the remaining part to be zeroes

解法

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