POJ 2924 Gauß in Elementary School（水~）

Description
给出两个数s和e，输出s+…+e
Input
第一行为用例组数t，每组用例占一行包括两个整数s和e(-10^9<=s,e<=10^9)
Output
Sample Input
3
1 100
-11 10
-89173 938749341
Sample Output

Scenario #1:
5050

Scenario #2:
-11

Scenario #3:
440625159107385260
Solution
水题
Code

#include<stdio.h>
typedef long long ll;
int main()
{
    int n,res=1;
    ll s,e,ss,ee;
    scanf("%d",&n);
    while(n)
    {
        scanf("%lld%lld",&s,&e);
        ss=s>=0?s:-s;
        ee=e>=0?e:-e;
        if(s>0&&e>0)
        {
            ss=(ss-1)*ss/2;
            ee=(ee+1)*ee/2;
        }
        else if(s<=0&&e>=0)
            {
                ss=(ss+1)*ss/2;
                ee=(ee+1)*ee/2; 
            }
            else if(s<0&&e<0)
                {
                    ss=(ss+1)*ss/2;
                    ee=(ee-1)*ee/2;
                }
        printf("Scenario #%d:\n",res);
        printf("%lld\n\n",ee-ss);
        res++;
        n--;
    }
    return 0;
}