[Leetcode] 401. Binary Watch 解题报告
来源:互联网 发布:达芬奇家具造假 知乎 编辑:程序博客网 时间:2024/06/16 16:44
题目:
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.
![](https://upload.wikimedia.org/wikipedia/commons/8/8b/Binary_clock_samui_moon.jpg)
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".
思路:
也是一道典型的深度优先搜索题目。在DFS中需要完成的任务是:计算有k个灯亮的时候,有多少种二进制数字的可能性(当然由于小时和分钟的取值范围不同,在DFS中需要设置不同的终止条件)。然后我们就分别遍历在num个亮的灯中,有i个处于小时位置,有num - i个处于分钟位置时的二进制可能性,并且将它们进行组合。
代码:
class Solution {public: vector<string> readBinaryWatch(int num) { vector<string> ans; for(int i = max(0, num - 6); i <= min(4, num); ++i) { vector<int> vec1, vec2; DFS(4, i, 0, 0, vec1); // i LEDs representing the hour are on DFS(6, num - i, 0, 0, vec2); // num - i LEDs representing the minite are on for(auto val1 : vec1) { for(auto val2 : vec2) { string minute = (to_string(val2).size() == 1 ? "0" : "") + to_string(val2); ans.push_back(to_string(val1) + ":" + minute); } } } return ans; }private: void DFS(int len, int k, int index, int val, vector<int>& vec) { if(k == 0 && len == 4 && val < 12) { // hour termination condition vec.push_back(val); } if(k == 0 && len == 6 && val < 60) { // minute termination condition vec.push_back(val); } if(index == len || k == 0) { return; } DFS(len, k, index + 1, val, vec); // case that the index-th LED is off DFS(len, k - 1, index + 1, val + pow(2, index), vec); // case that the index-th LED is on }};
阅读全文
0 0
- [leetcode] 401. Binary Watch 解题报告
- LeetCode 401. Binary Watch 解题报告
- [Leetcode] 401. Binary Watch 解题报告
- 【LeetCode】Binary Watch 解题报告
- Leetcode 401. Binary Watch 二进制的表 解题报告
- 【Leetcode】401. Binary Watch
- [LeetCode]401. Binary Watch
- LeetCode 401. Binary Watch
- [leetcode]401. Binary Watch
- Leetcode 401. Binary Watch
- LeetCode 401. Binary Watch
- LeetCode 401. Binary Watch
- LeetCode 401. Binary Watch
- leetcode 401. Binary Watch
- 【LeetCode】 401. Binary Watch
- [LeetCode]401. Binary Watch
- 401. [LeetCode]Binary Watch
- Leetcode 401. Binary Watch
- 佛山微信小程序
- 线程安全问题
- 《JAVA源码分析》:ArrayList
- HDU 4006:The kth great number(数据结构?)
- windows 实例崩溃恢复
- [Leetcode] 401. Binary Watch 解题报告
- Oculus 0.7.0 SDK DX11渲染流程
- bzoj2836魔法树 树剖
- MIPI-DSI 三种 Video Mode 理解
- intellij idea之debug
- 物联网核心安全系列——物联网安全需求
- js,jquery获取和格式化时间方法总结
- fastjson与spring mvc整合的配置
- 微信小程序开发