[每日 LeetCode] 905. Sort Array By Parity

Description:

Given an array A of non-negative integers, return an array consisting of all the even elements of A , followed by all the odd elements of A .

You may return any answer array that satisfies this condition.

Example 1:

Input: [3,1,2,4]
Output: [2,4,3,1]
The outputs [4,2,3,1], [2,4,1,3], and [4,2,1,3] would also be accepted.

Note:

1. 1 <= A.length <= 5000
2. 0 <= A[i] <= 5000

思路：题目要求数组中所有的奇数要在偶数后面，考虑使用两个变量分别从数组头开始，一个向前移动（当前数为偶数），一个用来交换（当前数为奇数）。

我的 C++ 代码

class Solution {
public:
    vector<int> sortArrayByParity(vector<int>& A) {
         for (int i = 0, j = 0; j < A.size(); j++){
            if (A[j] % 2 == 0) 
              swap(A[i++], A[j]);
         }
        return A;
    }
};

运行时间：32ms
运行内存：11.4M