Description
You are given N sticks having distinct lengths; you have to form some triangles using the sticks. A triangle is valid if its area is positive. Your task is to find the number of ways you can form a valid triangle using the sticks.
Input
Input starts with an integer T (≤ 10), denoting the number of test cases.
Each case starts with a line containing an integer N (3 ≤ N ≤ 2000). The next line contains N integers denoting the lengths of the sticks. You can assume that the lengths are distinct and each length lies in the range [1, 109].
Output
For each case, print the case number and the total number of ways a valid triangle can be formed.
Sample Input
3
5
3 12 5 4 9
6
1 2 3 4 5 6
4
100 211 212 121
Sample Output
Case 1: 3
Case 2: 7
Case 3: 4
#include<cstdio>
#include<cstring>
#include<cmath>
#include<queue>
#include<algorithm>
using namespace std;
int s[2001];
int main()
{
int t;
scanf("%d",&t);
int ans=0;
while(t--)
{
int n,q;
ans++;
scanf("%d",&n);
for(int i=0;i<n;i++)
{
scanf("%d",&s[i]);
}
sort(s,s+n);
int num=0;
for(int i=0;i<n;i++)
{
for(int j=i+1;j<n;j++)
{
q=s[j]+s[i];
int id=lower_bound(s+j,s+n,q)-s;
if(j==id)
{
continue;
}
num=num+(id-j-1);
}
}
printf("Case %d: %d
",ans,num);
}
return 0;
}