백준 1157번 C++

#include <iostream>
#include <string>
#include <algorithm>

using namespace std;
const int MAX = 26;
int answer[MAX];

int main(void) {
	int maxnum = -1, counts = 0;;
	string s;
	cin >> s;
	
	for (int i = 0; i < s.length(); i++) {
		if (s[i] >= 'A' && s[i] <= 'Z') {
			answer[s[i] - 'A'] ++;
			maxnum = max(maxnum, answer[s[i] - 'A']);
		}
		else if (s[i] >= 'a' && s[i] <= 'z') {
			answer[s[i] - 'a'] ++;
			maxnum = max(maxnum, answer[s[i] - 'a']);
		}
	}
	for (int i = 0; i < MAX; i++) {
		if (answer[i] == maxnum) {
			s = i + 'A';
			counts++;
		}
	}
	if (counts > 1)
		cout << "?" << endl;
	else
		cout << s << endl;
	return 0;
}