백준 - 1292 c++

www.acmicpc.net/problem/1292

1292번: 쉽게 푸는 문제

 

#include <iostream>
using namespace std;
int main() {
    int n, m;
    int arr[1001];
    int cnt = 1, sum = 0;
    cin >> n >> m;
    for (int i = 1, cnt = 1; i <= 1000 ; cnt++) {
        for (int j = 0; j < cnt; j++) {
            arr[i] = cnt;
            i++;
            if (i == 1001) break;
        }
        if (i == 1001) break;
    }
    
    for (int i = n; i <= m; i++){
        sum += arr[i];
    }
    cout << sum;
    return 0;
}