//401
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.
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 = 1Return: ["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".
#include <iostream>
#include <vector>
#include <bitset>
#include <string>
using namespace std;
class Solution {
public:
vector<string> readBinaryWatch(int num) {
//permutation
vector<string> res;
for(int h=0;h<12;h++){
for(int m=0;m<60;m++){
if(bitset<10>(h<<6 | m).count()==num){
//left move,right->left become empty
//becom 10 bit h--4 bit ，m--6 bit
res.push_back(to_string(h)+(m<10 ? ":0":":")+to_string(m));
}
}
}
return res;
}
};
int main(){
int num=1;
vector<string> res;
res=Solution().readBinaryWatch(num);
for(int i=0;i<res.size();i++){
for(int j=0;j<res[i].size();j++){
cout<<res[i][j]<<" ";
}
cout<<endl;
}
return 0;
}
