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.

理解一下
给一个数组, 进行排序.
偶数在前, 奇数在后

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

我的解法

class Solution {
    func sortArrayByParity(_ A: [Int]) -> [Int] {
        var first = 0
        var last = A.count - 1
        var list = A
        while first < last {
            
            if 0 != list[first] % 2 { // 第一位基数
                list.swapAt(first, last)
                last -= 1
            } else {
                first += 1
            }
            
            if 0 == list[last] % 2 { // 最后一位偶数
                list.swapAt(first, last)
                first += 1
            } else {
                last -= 1
            }
        }
        
        return list
    }
}

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