POJ 3318 Matrix Multiplication(随机算法)

题目链接

随机算法使劲水...srand((unsigned)time(0))比srand(NULL)靠谱很多，可能是更加随机。

 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
 #include <map>
 #include <ctime>
 #include <cmath>
 using namespace std;
 #define LL __int64
 int a[][],b[][],c[][];
 int main()
 {
     int i,j,k,flag,n;
     srand((unsigned)time());
     while(scanf("%d",&n)!=EOF)
     {
         for(i = ; i <= n; i ++)
         {
             for(j = ; j <= n; j ++)
                 scanf("%d",&a[i][j]);
         }
         for(i = ; i <= n; i ++)
         {
             for(j = ; j <= n; j ++)
                 scanf("%d",&b[i][j]);
         }
         for(i = ; i <= n; i ++)
         {
             for(j = ; j <= n; j ++)
                 scanf("%d",&c[i][j]);
         }
         flag = ;
         for(i = ; i <= &&flag; i ++)
         {
             LL temp = ;
             int x,y;
             x = rand()%n + ;
             y = rand()%n + ;
             for(k = ; k <= n; k ++)
             {
                 temp += a[x][k]*b[k][y];
             }
             if(temp != c[x][y])
                 flag = ;
         }
         if(flag)
             printf("YES\n");
         else
             printf("NO\n");
     }
     return ;
 }