LeetCode5661. 替换隐藏数字得到的最晚时间

 法一、直接暴力枚举

class Solution {
public:
    bool check(string time,string res){
        for(int i = 0;i < 5;i++){
            if(time[i] == res[i] || time[i] == '?') 
                continue;
            return false;
        }
        return true;
    }
    string maximumTime(string time) {
        for(int i = 23;i >= 0;i--){
            for(int j = 59;j >= 0;j--){
                char res[10];
                sprintf(res,"%02d:%02d",i,j);
                if(check(time,res))
                    return res;
            }
        }
        return "";
    }
};

 实质就是正则表达式匹配，从后往前暴力枚举，查看是否匹配。

学习sprintf 的用法

法二、直接模拟

class Solution {
public:
    string maximumTime(string time) {
        if(time[0] == '?' ){
            if(time[1] == '0' || time[1] == '1'||time[1] == '2' || time[1] == '3' || time[1] == '?' )
                time[0] = '2';
            else 
                time[0] = '1';
        }
        if(time[1] == '?'){
            if(time[0] == '2') time[1] = '3';
            else time[1] = '9';
        }
        if(time[3] == '?' ) time[3] = '5' ;
        if(time[4] == '?' ) time[4] = '9' ;
        return time;
    }
};