水题（辅助数组，注意vector指定分配空间大小）

922. Sort Array By Parity II

Easy

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Given an array ​

​A​

​ of non-negative integers, half of the integers in A are odd, and half of the integers are even.

Sort the array so that whenever ​

​A[i]​

​​ is odd, ​

​i​

​​ is odd; and whenever ​

​A[i]​

​​ is even, ​

​i​

​ is even.

You may return any answer array that satisfies this condition.

Example 1:

Input: [4,2,5,7]

Output: [4,5,2,7]

Explanation: [4,7,2,5], [2,5,4,7], [2,7,4,5] would also have been accepted.

1. ​

   ​2 <= A.length <= 20000​

   ​
2. ​

   ​A.length % 2 == 0​

   ​
3. ​

   ​0 <= A[i] <= 1000​

   ​

class Solution {
public:
    vector<int> sortArrayByParityII(vector<int>& A) {
        int length = A.size();
        vector<int>Result(length);
        if(length == 0){return Result;}
        vector<int> odd(length / 2);//奇数数组
        vector<int> even(length / 2);//偶数数组
        int OddIndex = 0;int EvenIndex = 0;
        for(int i = 0;i < A.size();i ++){
            if(A[i] % 2 == 0){
                even[EvenIndex++] = A[i];
            }
            else{
                odd[OddIndex++] = A[i];
            }
        }
        for(int i = 0;i < length;i += 2){
            Result[i] = even[i / 2];
            Result[i + 1] = odd[i / 2];
        }
        return Result;
    }
};