Leetcode 401. Binary Watch

文章作者：Tyan
博客：noahsnail.com  |  CSDN  |  简书

1. Description

2. Solution

• Version 1

class Solution {
public:vector<string> readBinaryWatch(int num) {vector<string> result;vector<int> hourBits = countBits(11);vector<int> miniteBits = countBits(59);for(int i = 0; i < 12; i++) {for(int j = 0; j < 60; j++) {if(hourBits[i] + miniteBits[j] == num) {string s = to_string(i) + (j<10?(":0" + to_string(j)):(":" + to_string(j)));result.push_back(s);}}}return result;}private:vector<int> countBits(int num) {vector<int> array(num + 1, 0);for(int i = 1; i <= num; i++) {array[i] = array[(i & (i - 1))] + 1;}return array;}
};

• Version 2

class Solution {
public:vector<string> readBinaryWatch(int num) {vector<string> result;for(int i = 0; i < 12; i++) {for(int j = 0; j < 60; j++) {if(bitset<10>((i << 6) + j).count() == num) {string s = to_string(i) + (j<10?(":0" + to_string(j)):(":" + to_string(j)));result.push_back(s);}}}return result;}
};

• Version 3

class Solution {
public:vector<string> readBinaryWatch(int num) {vector<string> result;for(int h = 0; h < 12; h++) {for(int m = 0; m < 60; m++) {if(bitset<10>((h << 6) + m).count() == num) {result.emplace_back(to_string(h) + (m<10?(":0" + to_string(m)):(":" + to_string(m))));}}}return result;}
};

Reference

1. https://leetcode.com/problems/binary-watch/description/