LevOJ P1401 矩阵连乘

#include 
#include 
using namespace std;
int w[1000], q[1000][1000];
int r[500][500];
int course(int i, int j) 
{
    int x, t;
    int k;
    if(r[i][j]>=0)
        return r[i][j];
    if(i == j)
        return 0;
    if(i == j-1)
    {
        q[i][i+1] = i;
        r[i][j] = w[i] * w[i+1] * w[i+2];
        return r[i][j];
    }
    x = course(i, i) + course(i+1, j) + w[i] * w[i+1] * w[j+1];
    q[i][j]=i;
    for(k = i+1; k> n && n!=0)
    {
        int flag = 1;
        memset(w,0,sizeof(w));
        memset(q,0,sizeof(q));
        memset(r,0,sizeof(r));
        for(i = 1; i <= n; i++)
        {
            cin >> w[i];
            if(i > 1) 
            {
                if(w[i] != tmp)
                {
                    flag = 0;
                }
            }
            cin >> tmp;
        }
        w[i] = tmp;//将矩阵的行列数量化成一列表达
        for(i = 1; i<= n; i++)
        {
            for(j = 1; j <= n; j++)
            {
                r[i][j] = -1;
            }
        }
        if(flag)
            cout << course(1, n) << endl;
        else
            cout << "invalid argument" << endl;
    }
    return 0;
}

使用动态规划算法就能解决，如果不知道动态规划怎么写，出门右转bilibili