Latest Time by Replacing Hidden Digits

<-E 1736> Latest Time by Replacing Hidden Digits

class Solution {
public:
    string maximumTime(string time) {
        if(time[0] == '?' and time[1]>='0' and time[1]<='3') 
            time[0] = '2';
        
        if(time[0] == '?' and time[1]>='4' and time[1]!='?') 
            time[0] = '1';
        
        if(time[0] == '?' and time[1] == '?') {
            time[0] = '2';
            time[1] = '3';
        }
        
        
        if(time[1] == '?' and time[0] == '2') {
            time[1] = '3';
        }
        
        if(time[1] == '?' and time[0]!='2') 
            time[1] = '9';
        
        if(time[3] == '?') 
            time[3] = '5';

        if(time[4] == '?') 
            time[4] = '9';
        
        return time;
    }
};