[LeetCode]401. Binary Watch &bitset的用法&to_string

A binary watch has 4 LEDs on the top which represent the hours (0-11), and the 6 LEDs on the bottom represent the minutes (0-59).

Each LED represents a zero or one, with the least significant bit on the right.

For example, the above binary watch reads "3:25".

Given a non-negative integer n which represents the number of LEDs that are currently on, return all possible times the watch could represent.

Example:

Input: n = 1
Return: ["1:00", "2:00", "4:00", "8:00", "0:01", "0:02", "0:04", "0:08", "0:16", "0:32"]

Note:

• The order of output does not matter.
• The hour must not contain a leading zero, for example "01:00" is not valid, it should be "1:00".
• The minute must be consist of two digits and may contain a leading zero, for example "10:2" is not valid, it should be "10:02".

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思路：遍历，利用bitset&to_string

#include<iostream>#include<bitset>#include<string>#include<vector>using namespace std; vector<string> readBinaryWatch(int num) {vector<string> res;for(int h=0;h<12;h++){for(int m=0;m<60;m++){if((bitset<10>(h*64+m)).count()==num)res.push_back(to_string(h) + (m < 10 ? ":0" : ":") + to_string(m));}}return res;}int main(){vector<string> res=readBinaryWatch(1);for(int i=0;i<res.size();i++)cout<<res[i]<<endl;}