[leetcode-283]Move Zeroes(java)

问题描述：

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.

分析：这里使用了两个索引，一个指向0，一个指向非0，二者分别向后遍历，当出现一对（0，非0）时，交换二者位置，这样当遍历到结束时，此时0也就被移动到了最后。因为每个节点最多被访问两次，所以时间复杂度为O(n).

代码如下：340ms

[code]public class Solution {
    public void moveZeroes(int[] nums) {
        int zeroIndex = 0;
        int nonZeroIndex = 0;
        int size = nums.length;

        while(zeroIndex<size && nonZeroIndex<size){
            while(zeroIndex<size && nums[zeroIndex]!=0) zeroIndex++;
            while(nonZeroIndex < size && (nums[nonZeroIndex]==0 || nonZeroIndex<zeroIndex)) nonZeroIndex++;

            //swap the value
            if(zeroIndex<size && nonZeroIndex<size){
                nums[zeroIndex++] = nums[nonZeroIndex];
                nums[nonZeroIndex++] = 0;
            }
        }
    }
}