Codeforces Gym100735 D.Triangle Formation (KTU Programming Camp (Day 1) Lithuania, Birˇstonas, August 19, 2015)

日常训练题解

D.Triangle Formation

You are given N wooden sticks. Your task is to determine how many triangles can be made from the given sticks without breaking them. Each stick can be used in at most one triangle.

Input

The first line of each test case contains the number of sticks N. (1 ≤ N ≤ 15)

The second line of each test case contains N integers len_i that are the lengths of the sticks. (1 ≤ len_i ≤ 10⁹).

Output

Output single integer R – the maximal number of triangles.

Example

Input

2
1 1

Output

0

Input

3
2 2 2

Output

1

Input

6
2 2 3 4 5 6

Output

2

暴力就可以了

代码:

 #include<cstring>
 #include<cstdio>
 #include<iostream>
 #include<algorithm>
 using namespace std;
 int a[],flag[];
 int main(){
     int n;
     while(~scanf("%d",&n)){
         memset(flag,,sizeof(flag));
         for(int i=;i<n;i++){
             scanf("%d",&a[i]);
             flag[i]=;
         }
         sort(a,a+n);
         if(n<=)printf("0\n");
         else{
             int num=;
             for(int i=;i<n;i++){
                 for(int j=;j<n;j++){
                     for(int k=;k<n;k++){
                         if(i!=j&&i!=k&&j!=k&&flag[i]==&&flag[j]==&&flag[k]==&&a[i]+a[j]>a[k]&&a[i]+a[k]>a[j]&&a[k]+a[j]>a[i]){
                             num++;flag[i]=;flag[j]=;flag[k]=;
                         }
                         else continue;
                     }
                 }
             }
             printf("%d\n",num);
         }
     }
     return ;
 }

溜了溜了。。。