qiaoxu123
11/7/2018 - 12:47 AM

905. Sort Array By Parity

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

test.cpp
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//使用额外空间进行寄存
//28 ms
class Solution {
public:
    vector<int> sortArrayByParity(vector<int>& A) {
        vector<int> array;
        for(int i = 0;i < A.size();++i){
            if(A[i] % 2 == 0 || A[i] == 0){
                array.push_back(A[i]);
                A[i] = -1;
            }
        }
        for(int i = 0;i < A.size();++i){
            if(A[i] > 0)
                array.push_back(A[i]);
        }
        return array;
    }
};
test2.cpp
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//原地修改，复杂度为O(n)
//28 ms
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;
    }
};