HDU 1224 无环有向最长路

用bellman_ford的方法，将中间不断取较小值，修改为取较大值就可以了

 #include <cstdio>
 #include <cstring>
 #include <iostream>
 using namespace std;
 const int N = ;
 int dp[N] , k , first[N] , val[N] , x , y , fa[N] , rec[N];

 struct Edge{
     int x , y , next , d;
 }e[N*N];

 void add_edge(int x , int y , int d)
 {
     e[k].x = x , e[k].y = y , e[k].next = first[x] , e[k].d = d;
     first[x] = k++;
 }

 int main()
 {
     int T , n , cas = ;
     scanf("%d" , &T);
     while(T--){
         scanf("%d" , &n);
         for(int i =  ; i<=n ; i++)
             scanf("%d" , val+i);
         val[n+] = ;

         int m;
         scanf("%d" , &m);
         k=;
         for(int i =  ; i<m ; i++){
             scanf("%d%d" , &x , &y);
             add_edge(x , y , val[y]);
         }

         memset(dp ,  , sizeof(dp));
         memset(fa ,  , sizeof(fa));
         for(int i =  ; i<=n ; i++){
             for(int j =  ; j<k ; j++){
                 int u = e[j].x , v = e[j].y;
                 if(dp[v] < dp[u] + e[j].d){
                     dp[v] = dp[u] + e[j].d;
                     fa[v] = u;
                    // cout<<"here: "<<u<<" "<<v<<" "<<fa[v]<<" "<<dp[v]<<endl;
                 }
             }
         }

         printf("CASE %d#\npoints : %d\ncircuit : " , ++cas , dp[n+]);
         int cnt =  , la = n+;
         rec[cnt++] = ;
         while(fa[la]){
             rec[cnt++] = fa[la];
             la = fa[la];
         }
         for(int i = cnt- ; i>= ; i--)
             printf("%d->" , rec[i]);
         printf("%d\n" , rec[]);
         if(T>) puts("");
     }
     return ;
 }