27. leetcode 401. Binary Watch

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".

C++中int转string

方法一：

#include<strstream> #include<string>

string s; int a = 1009; strstream ss; ss << a; ss >> s; cout <<s<< endl;

方法二：

#include<string> string s; int a=1009; char buff[250]; sprintf_s(buff,”%d”,a); s=buff;

简单思路：时最多3个1，分最多5个1。直接看代码吧！