bzoj1497 最大获利 最大权闭合图

题意：如题。。中文题。。

思路：很裸的最大权闭合图，用户的点权为所获得利润，所用中转站的点权为成本的负值，转换成最小割 的模型即可。详见代码：

// file name: bzoj1497.cpp //// author: kereo //// create time:  2014年11月13日 星期四 19时28分08秒 ////***********************************//#include<iostream>#include<cstdio>#include<cstring>#include<queue>#include<set>#include<map>#include<vector>#include<stack>#include<cmath>#include<string>#include<algorithm>using namespace std;typedef long long ll;const int sigma_size=26;const int MAXN=55000+100;const double eps=1e-8;const int inf=0x3fffffff;const int mod=1000000000+7;#define L(x) (x<<1)#define R(x) (x<<1|1)int n,m,edge_cnt,top;int head[MAXN],depth[MAXN],cur[MAXN],gap[MAXN],que[MAXN],s[MAXN];struct Edge{int v,cap,flow,next;}edge[MAXN<<3];void addedge(int u,int v,int cap){edge[edge_cnt].v=v;edge[edge_cnt].cap=cap; edge[edge_cnt].flow=0;edge[edge_cnt].next=head[u]; head[u]=edge_cnt++;}void init(){edge_cnt=top=0;memset(head,-1,sizeof(head));}void bfs(int st,int ed){memset(gap,0,sizeof(gap));memset(depth,-1,sizeof(depth));int front=0,rear=0; gap[0]=1;depth[ed]=0; que[rear++]=ed;while(front!=rear){int u=que[front++];for(int i=head[u];i!=-1;i=edge[i].next){int v=edge[i].v;if(depth[v]!=-1) continue;que[rear++]=v;depth[v]=depth[u]+1; gap[depth[v]]++;}}}int isap(int st,int ed){bfs(st,ed);memcpy(cur,head,sizeof(head));int u=st,ans=0;while(depth[u]<n+m+2){if(u == ed){int Min=inf,ins;for(int i=0;i<top;i++){if(edge[s[i]].cap-edge[s[i]].flow<Min){Min=edge[s[i]].cap-edge[s[i]].flow;ins=i;}}for(int i=0;i<top;i++)edge[s[i]].flow+=Min,edge[s[i]^1].flow-=Min;ans+=Min; top=ins; u=edge[s[top]^1].v;continue;}int v,flag=0;for(int i=cur[u];i!=-1;i=edge[i].next){v=edge[i].v;if(edge[i].cap-edge[i].flow && depth[v]+1 == depth[u]){flag=1; cur[u]=i;break;}}if(flag){s[top++]=cur[u]; u=v;continue;}int d=n+m+2;for(int i=head[u];i!=-1;i=edge[i].next){int v=edge[i].v;if(edge[i].cap-edge[i].flow && depth[v]<d){d=depth[v]; cur[u]=i;}}gap[depth[u]]--;if(!gap[depth[u]]) return ans;depth[u]=d+1; gap[depth[u]]++;if(u!=st) u=edge[s[--top]^1].v;}return ans;}int main(){while(~scanf("%d%d",&n,&m)){init();int x;for(int i=1;i<=n;i++){scanf("%d",&x);addedge(i+m,n+m+1,x); addedge(n+m+1,i+m,0);}int u,v,c;int sum=0;for(int i=1;i<=m;i++){scanf("%d%d%d",&u,&v,&c);addedge(0,i,c); addedge(i,0,0);sum+=c;addedge(i,u+m,inf); addedge(u+m,i,0);addedge(i,v+m,inf); addedge(v+m,i,0);}sum-=isap(0,n+m+1);printf("%d\n",sum);}return 0;}