/**
 * @param {number[]} nums
 * @return {number[]}
 */
var findNumsAppearOnce = function(nums) {
    let xy = 0;
    nums.forEach( (value, index) => {
        xy ^= value;
    });
    // console.log(xy);
    // console.log(xy.toString(2));
    let k = 0;
    while(!(xy >> k & 1)) k ++; // 如果第k位为0 k++
    let X = 0;
    nums.forEach( (value, index) => {
        if(value >> k & 1){
            X ^= value;
        }
    });
    let Y = 0;
    Y = xy ^ X;
    return [X, Y];   
};