poj 1695 动态规划

思路：和黑书上的跳舞机类似

#include<map>
#include<set>
#include<cmath>
#include<queue>
#include<cstdio>
#include<vector>
#include<string>
#include<cstdlib>
#include<cstring>
#include<iostream>
#include<algorithm>
#define Maxn 31
#define Maxm 100010
#define LL __int64
#define Abs(x) ((x)>0?(x):(-x))
#define lson(x) (x<<1)
#define rson(x) (x<<1|1)
#define inf 0x7fffffff
#define Mod 1000000007
using namespace std;
int dp[Maxn][Maxn][Maxn][Maxn];
int dis[Maxn][Maxn];
int main()
{
    int t,n,i,j,x,k,r;
    scanf("%d",&t);
    while(t--){
        memset(dis,0,sizeof(dis));
        memset(dp,48,sizeof(dp));
        scanf("%d",&n);
        for(i=1;i<n;i++){
            for(j=i+1;j<=n;j++){
                scanf("%d",&x);
                dis[i][j]=dis[j][i]=x;
            }
        }
        memset(dp[1],0,sizeof(dp[1]));
        for(i=2;i<=n;i++){
            for(j=1;j<=i-1;j++){
                for(k=1;k<=i-1;k++){
                    for(r=1;r<=i-1;r++){
                        dp[i][i][k][r]=min(dp[i][i][k][r],dp[i-1][j][k][r]+dis[j][i]);
                        dp[i][j][i][r]=min(dp[i][j][i][r],dp[i-1][j][k][r]+dis[k][i]);
                        dp[i][j][k][i]=min(dp[i][j][k][i],dp[i-1][j][k][r]+dis[r][i]);
                    }
                }
            }
        }
        int ans=100000000;
        for(i=1;i<=n;i++){
            for(j=1;j<=n;j++){
                for(k=1;k<=n;k++){
                    ans=min(dp[n][i][j][k],ans);
                }
            }
        }
        printf("%d
",ans);
    }
    return 0;
}