算法提高 矩阵乘法 区间dp

 1 #include<bits/stdc++.h>
 2 #include<iostream>
 3 #include<cstring>
 4 #include<cstdio>
 5 #include<algorithm>
 6 #include<vector>
 7 #define ll __int64
 8 #define PI acos(-1.0)
 9 using namespace std;
10 int n;
11 ll a[1005];
12 ll score[1005][1005];
13 int main()
14 {
15     scanf("%d",&n);
16     for(int i=1; i<=n+1; i++)
17         scanf("%I64d",&a[i]);
18     memset(score,0,sizeof(score));
19     for(int i=1; i<=n+1; i++)
20         for(int j=1; j<=n+1; j++)
21             score[i][j]=1000000000000000;
22     for(int i=1; i<=n; i++)
23         score[i][i+1]=0ll;
24     for(int i=n+1; i>=1; i--)
25     {
26         for(int j=i+1; j<=n+1; j++)
27         {
28             for(int k=i+1; k<j; k++)
29                 score[i][j]=min(score[i][j],score[i][k]+score[k][j]+a[k]*a[i]*a[j]);
30         }
31     }
32     printf("%I64d\n",score[1][n+1]);
33     return 0;
34 }