백준 1157번: 단어 공부

문제 출처: https://www.acmicpc.net/problem/1157

import java.io.BufferedReader;
import java.io.InputStreamReader;
 
public class Main {
    
    public static void main(String[] args) throws Exception {
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        String input = reader.readLine().toUpperCase();
        int[] arr = new int[26];
        
        for(int i=0 ; i<input.length() ; i++)
            arr[input.charAt(i)-65]++;
        
        int max = 0; 
        boolean isSame = false;
        int index = 0;
        
        for(int i=0 ; i<arr.length ; i++){
            if(max < arr[i]){
                max = arr[i];
                isSame = false;
                index = i;
            }
            else if(max == arr[i]){
                isSame = true;
            }
        }
        
        if(isSame)
            System.out.println("?");
        else
            System.out.println((char)(index+65));
    }
}