【Leetcode】905. 按奇偶性排序数组（Sort Array By Parity）

Leetcode - 905 Sort Array By Parity (Easy)

题目描述：排序数组使得偶数在前，奇数在后。

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.

解法一：额外数组

public int[] sortArrayByParity(int[] A) { int[] res = new int[A.length]; int index = 0; for (int i : A) { if (i % 2 == 0) res[index++] = i; } for (int i : A) { if (i % 2 == 1) res[index++] = i; } return res; }

解法二：双指针

public int[] sortArrayByParity(int[] A) { int left = 0, right = A.length - 1; while (right > left) { if (A[left] % 2 > A[right] % 2) { int tmp = A[left]; A[left] = A[right]; A[right] = tmp; } if (A[left] % 2 == 0) left++; if (A[right] % 2 == 1) right--; } return A; }