<4.1> 학습 회장(해쉬)

일단 코드 먼저 ...

package section4.question1;

import java.util.Scanner;

public class Main {

    public static char solution(char[] charArr, int N){

        int[] frequency = new int[26];

        for(int i=0; i<N; i++){
            frequency[charArr[i] - 'A']++;
        }

        int maxIdx = -1;
        int maxValue = -1;
        for(int i=0; i<26; i++){
            if(frequency[i] > maxValue){
                maxValue = frequency[i];
                maxIdx = i;
            }
        }

        return (char)(maxIdx + 'A');
    }

    public static void main(String[] args){

        //0. Scanner 준비
        Scanner sc = new Scanner(System.in);

        //1. 입력
        int N = sc.nextInt();
        sc.nextLine();
        char[] charArr = sc.nextLine().toCharArray();

        //2. solution() 호출
        char result = solution(charArr, N);

        //3. 결과 출력
        System.out.println(result);

    }
}