Record a question using bitset, it's really easy to use

Interview question 0504. Next number

Record the usage of bitset:

https://www.cnblogs.com/magisk/p/8809922.html

class Solution {
   public:
    vector<int> findClosedNumbers(int num) {
        bitset<32> small(num);
        bitset<32> bigger(num);

        int s = -1;
        // small, 10 转 01，1移到左侧
        for (int i = 1; i < 32; i++) {
            if (small[i] == 1 && small[i - 1] == 0) {
                small.flip(i);
                small.flip(i - 1);
                for (int left = 0, right = i - 2; left < right;) {
                    while (left < right && small[left] == 0) left++;
                    while (left < right && small[right] == 1) right--;
                    small.flip(left);
                    small.flip(right);
                }
                s = (int)small.to_ulong();
                break;
            }
        }

        // bigger, 01转10，1移到最右侧
        int b = -1;
        for (int i = 1; i < 32; i++) {
            if (bigger[i] == 0 && bigger[i - 1] == 1) {
                bigger.flip(i);
                bigger.flip(i - 1);

                for (int left = 0, right = i - 2; left < right;) {
                    while (left < right && bigger[left] == 1) left++;
                    while (left < right && bigger[right] == 0) right--;
                    bigger.flip(left);
                    bigger.flip(right);
                }
                b = (int)bigger.to_ulong();
                break;
            }
        }

        return {b, s};
    }
};