hdu 6201(最小费用最大流)

transaction transaction transaction

Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 132768/132768 K (Java/Others)
Total Submission(s): 1003    Accepted Submission(s):
488

Problem Description

Source

2017
ACM/ICPC Asia Regional Shenyang Online

直接构图 费用流跑一遍

 #include<iostream>
 #include<cstdio>
 #include<algorithm>
 #include<cstring>
 #include<cstdlib>
 #include<string.h>
 #include<set>
 #include<vector>
 #include<queue>
 #include<stack>
 #include<map>
 #include<cmath>
 typedef long long ll;
 typedef unsigned long long LL;
 using namespace std;
 const double PI=acos(-1.0);
 const double eps=0.0000000001;
 const int INF=0x3f3f3f3f;
 const int N=+;
 int a[N];
 int head[N];
 int dis[N];
 int pre[N];
 int vis[N];
 int tot;
 int m,n;
 struct node{
     int from,to,next,flow,cost;
 }edge[N<<];
 void init(){
     memset(head,-,sizeof(head));
     tot=;
 }
 void add(int u,int v,int c,int cost){
     edge[tot].from=u;
     edge[tot].to=v;
     edge[tot].flow=c;
     edge[tot].cost=cost;
     edge[tot].next=head[u];
     head[u]=tot++;
     edge[tot].from=v;
     edge[tot].to=u;
     edge[tot].flow=;
     edge[tot].cost=-cost;
     edge[tot].next=head[v];
     head[v]=tot++;
 }
 int spfa(int s,int t){
     memset(pre,-,sizeof(pre));
     memset(dis,INF,sizeof(dis));
     memset(vis,,sizeof(vis));
     queue<int>q;
     dis[s]=;
     vis[s]=;
     q.push(s);
     while(!q.empty()){
         int x=q.front();
         q.pop();
         vis[x]=;
         for(int i=head[x];i!=-;i=edge[i].next){
             int v=edge[i].to;
             if(edge[i].flow&&dis[v]>dis[x]+edge[i].cost){
                 dis[v]=edge[i].cost+dis[x];
                 pre[v]=i;
                 if(vis[v]==){
                     vis[v]=;
                     q.push(v);
                 }
 
             }
         }
     }
     if(pre[t]==-)return ;
     return ;
 }
 int MCMF(int s,int t){
     int flow=;
     int cost=;
     while(spfa(s,t)){
         int minn=INF;
         for(int i=pre[t];i!=-;i=pre[edge[i].from]){
             minn=min(minn,edge[i].flow);
         }
         for(int i=pre[t];i!=-;i=pre[edge[i].from]){
             edge[i].flow=edge[i].flow-minn;
             edge[i^].flow=edge[i^].flow+minn;
             cost=edge[i].cost+cost;
            // cout<<cost<<endl;
         }
         flow=flow+minn;
     }
     return cost;
 }
 int main(){
     int tt;
     scanf("%d",&tt);
     while(tt--){
         init();
         scanf("%d",&n);
         for(int i=;i<=n;i++){
             scanf("%d",&a[i]);
         }
         int s=;
         int s1=n+;
         int t=n+;
         add(s,s1,,);
         for(int i=;i<=n;i++){
             add(s1,i,,-a[i]);
         }
         for(int i=;i<=n;i++){
             add(i,t,,a[i]);
         }
         for(int i=;i<=n-;i++){
             int u,v,cost;
             scanf("%d%d%d",&u,&v,&cost);
             add(u,v,,cost);
             add(v,u,,cost);
         }
         cout<<abs(MCMF(s,t))<<endl;
     }
 }