比较容易理解的解题方法

#include <bits/stdc++.h>
using namespace std;
char c[] = {"0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ"};
string f(int a,int r){
	string s = "";
	while(a){
		s += c[a%r];
		a/=r;
	}
	reverse(s.begin(),s.end());//逆置字符串 
	return s;
}
int main(){
    long long a,b;
	int r;
	cin>>a>>b>>r;
	string s1,s2;
	s1 = f(a,r);
	s2 = f(b,r);
	if(s1 > s2){
		cout<<s1;
	}else{
		cout<<s2;
	}
    return 0;
}