백준 1292번

원본 : https://www.acmicpc.net/problem/1292

1292번: 쉽게 푸는 문제

 

풀이

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import java.util.StringTokenizer;

public class Main {
    private static final BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));

    public static void main(String[] args) throws Exception {
        List<Integer> list = new ArrayList<>();
        list.add(0);

        for (int i = 1; i < 1000; i++) {
            for (int j = 0; j < i; j++) {
                list.add(i);
            }

            if (list.size() > 1000) {
                break;
            }
        }

        StringTokenizer st = new StringTokenizer(bufferedReader.readLine());
        int a = Integer.parseInt(st.nextToken());
        int b = Integer.parseInt(st.nextToken());
        int sum = 0;

        for (int i = a; i <= b; i++) {
            sum += list.get(i);
        }

        System.out.println(sum);
    }
}