HDU 4920: Matrix multiplication

Posted 2020-10-08

///@date 9/26/2017
///@author Sycamore
///@link http://acm.hdu.edu.cn/showproblem.php?pid=4920
#include<bits/stdc++.h>
using namespace std;

int main()
{

   ios::sync_with_stdio(false);
   //cin.tie(nullptr);
   int n;
    while(cin>>n)
    {
        vector<vector<int>> A(n,vector<int>(n)),B(n,vector<int>(n)),C(n,vector<int>(n));
        for(auto &row:A)
            for(auto &el:row)
            {
                cin>>el;
                el%=3;
            }

        for(auto &row:B)
            for(auto &el:row)
            {
                cin>>el;
                el%=3;
            }
        for(int i=0;i<n;i++)
            for(int j=0;j<n;j++)
                if(A[i][j])
                    for(int k=0;k<n;k++)
                        C[i][k]+=A[i][j]*B[j][k];
                else continue;
        for(int i=0;i<n;i++)
            for(int j=0;j<n;j++)
            {
                cout<<C[i][j]%3<<(j==n-1?‘\n‘:‘ ‘);
            }
    }

}