[백준] 1292번 : 쉽게 푸는 문제 - C

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

#include<stdio.h>

int main() {
    int n,m;
    scanf("%d %d",&n,&m);
    int num=0;
    int a=0;
    int count=0;
    for(int i=1;;i++){
        count+=i;
        a+=i*i;
        if(n-count-1<=i && n!=1){
            num-=a;
            num-=(n-count-1)*(i+1);
            n=10000;
        }
        if(m-count-1<=i){
            num+=a;
            num+=(m-count)*(i+1);
            break;
        }
    }
    printf("%d",num);
}