POJ 3318-Matrix Multiplication first solves the problem with randomization...

Randomization is still very powerful... the most impressive thing is that the previous handwritten fast sorting ~~ Generally, adding a randomization will make the time not consumed by the input data more stable ..

This question is a character question... it cannot be handed over many times. I finally handed over several times...

 

Program:

 #include<iostream>   #include<stack>   #include<queue>   #include<stdio.h>   #include<algorithm>   #include<string.h>   #include<time.h>   #include<cmath>   #define ll long long   #define oo 1000000007   #define MAXN 505   using namespace std;   int n,M[3][MAXN][MAXN];  bool judge()  {        int t,i,j,x,y,p,d;         for (t=1;t<=60000;t++)        {                y=rand()%n;               x=rand()%n;               d=0;               for (p=0;p<n;p++)                  d+=M[0][y][p]*M[1][p][x];               if (d!=M[2][y][x]) return false;        }        return true;  }   int main()  {        int i,j,x;         scanf("%d",&n);        for (x=0;x<3;x++)           for (i=0;i<n;i++)             for (j=0;j<n;j++)                scanf("%d",&M[x][i][j]);        srand((unsigned)time(NULL));        if (judge()) printf("YES\n");               else  printf("NO\n");        return 0;  }