README.md

905. Sort Array By Parity

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.

Note:

1. 2 <= A.length <= 20000
2. A.length % 2 == 0
3. 0 <= A[i] <= 1000

Solutions (Java)

1.Tow Pointer

class Solution {
    public int[] sortArrayByParityII(int[] A) {
        int j = 1, tmp = 0;
        for(int i = 0; i < A.length - 1; i += 2){
            if(A[i] % 2 == 1){ 
                while(A[j] % 2 != 0){
                    j += 2;
                }
                tmp = A[j];
                A[j] = A[i];
                A[i] = tmp;
                }
        }
        return A;
    }
}