给你三个矩阵A，B，C。让你判断A*B是否等于C。
随机一组数据，然后判断乘以A，B之后是否与乘C之后相等。
很扯淡的啊，感觉这种算法不严谨啊、、、
| Time Limit: 2000MS | Memory Limit: 65536K | |
| Total Submissions: 16255 | Accepted: 3515 |
Description
You are given three n × n matrices A, B and C. Does the equation A × B = C hold true?
Input
The first line of input contains a positive integer n (n ≤ 500) followed by the the three matrices A, B and C respectively. Each matrix‘s description is a block of n × n integers.
It guarantees that the elements of A and B are less than 100 in absolute value and elements of C are less than 10,000,000 in absolute value.
Output
Output "YES" if the equation holds true, otherwise "NO".
Sample Input
2 1 0 2 3 5 1 0 8 5 1 10 26
Sample Output
YES
Hint
#include <stdio.h>
#include <string.h>
#include <iostream>
#include <algorithm>
#include <time.h>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <string>
#include <math.h>
#include <stdlib.h>
#define max( x, y ) ( ((x) > (y)) ? (x) : (y) )
#define min( x, y ) ( ((x) < (y)) ? (x) : (y) )
#define Mod 1000000007
#define LL long long
using namespace std;
const int maxn = 510;
int a[maxn][maxn];
int b[maxn][maxn];
int c[maxn][maxn];
int f[maxn];
int aa[maxn];
int bb[maxn];
int cc[maxn];
int main()
{
int n;
cin >>n;
memset(aa, 0, sizeof(aa));
memset(bb, 0, sizeof(bb));
memset(cc, 0, sizeof(cc));
for(int i = 0; i < n; i++)
for(int j = 0; j < n; j++) scanf("%d",&a[i][j]);
for(int i = 0; i < n; i++)
for(int j = 0; j < n; j++) scanf("%d",&b[i][j]);
for(int i = 0; i < n; i++)
for(int j = 0; j < n; j++) scanf("%d",&c[i][j]);
srand((unsigned int)time(0));
for(int i = 0; i < n; i++)
f[i] = rand()%100;
for(int i = 0; i < n; i++)
{
for(int j = 0; j < n; j++)
{
bb[i] += b[i][j]*f[j];
cc[i] += c[i][j]*f[j];
}
}
for(int i = 0; i < n; i++)
for(int j = 0; j < n; j++) aa[i] += a[i][j]*bb[j];
int flag = 0;
for(int i = 0; i < n; i++)
{
if(aa[i] != cc[i])
{
flag = 1;
break;
}
}
if(flag)
cout<<"NO"<<endl;
else
cout<<"YES"<<endl;
}
POJ 3318 Matrix Multiplication(随机化算法),布布扣,bubuko.com
POJ 3318 Matrix Multiplication(随机化算法)
原文：http://blog.csdn.net/xu12110501127/article/details/38374323