PAT B -1056 and the number of combinations (15 minutes)

Click on the link full solution summary PAT B -AC

topic:

Given N non-zero digit, with which any two numbers can be combined into a two-digit number. 2 requires that all possible combinations of numbers and out. 2,5,8 example given, it can be combined: 25,28,52,58,82,85, and 330 thereof.

Input formats:
on a single line is given to N (1 <N <10) , followed by analysis of the N different non-zero digit. Between numbers separated by a space.

Output Format:
Output all possible combinations of 2 digits and out.

Sample input:

3 2 8 5

Sample output:

330

My code:

#include<iostream>
#include<cstdio>
#include<vector>
#include<string>
#include<set>
#include<map>
#include<algorithm>
#include<cmath>
#include<ctime>
#include<cstring>
#include<sstream>
using namespace std;
//有的时候题目是一起做的，所以会有不需要的头文件

int main()
{
    int N;
    cin>>N;
    int sum=0;
    for(int i=0;i<N;i++)
    {
        int t;
        cin>>t;
        sum=sum + 11*t*(N-1);
    }
    cout<<sum;
    return 0;
}