剑指 Offer 56 - I. 数组中数字出现的次数

class Solution {
    public int[] singleNumbers(int[] nums) {
        // 相同 bit 异或为 0, 不同 bit 异或为 1

        int aXorB = 0;
        for (int num : nums) {
            aXorB ^= num;
        }

        int k = 1;
        while ((k & aXorB) == 0) {
            k <<= 1;
        }

        int a = 0, b = 0;
        for (int num : nums) {
            if ((num & k) != 0) {
                a ^= num;
            } else {
                b ^= num;
            }
        }

        return new int[]{a, b};
    }
}

Reference