loj 1155(最大流）

题目链接：http://acm.hust.edu.cn/vjudge/problem/viewProblem.action?id=26869
思路：题目还是比较水的，由于点也有容量，则必须拆点，然后跑最大流。
  1 #include<iostream>
  2 #include<cstdio>
  3 #include<cstring>
  4 #include<algorithm>
  5 #include<queue>
  6 using namespace std;
  7 #define MAXN 222
  8 #define MAXM 222222
  9 #define inf 1<<30
 10 #define FILL(a,b) memset(a,b,sizeof(a))
 11 
 12 struct Edge{
 13     int v,cap,next;
 14 }edge[MAXM];
 15 
 16 int n,m,vs,vt,NV,NE,Cap[MAXN];
 17 int head[MAXN];
 18 
 19 void Insert(int u,int v,int cap)
 20 {
 21     edge[NE].v=v;
 22     edge[NE].cap=cap;
 23     edge[NE].next=head[u];
 24     head[u]=NE++;
 25 
 26     edge[NE].v=u;
 27     edge[NE].cap=0;
 28     edge[NE].next=head[v];
 29     head[v]=NE++;
 30 }
 31 
 32 int level[MAXN],gap[MAXN];
 33 void bfs(int vt)
 34 {
 35     FILL(level,-1);
 36     FILL(gap,0);
 37     queue<int>que;
 38     que.push(vt);
 39     level[vt]=0;
 40     gap[0]++;
 41     while(!que.empty()){
 42         int u=que.front();
 43         que.pop();
 44         for(int i=head[u];i!=-1;i=edge[i].next){
 45             int v=edge[i].v;
 46             if(level[v]!=-1)continue;
 47             level[v]=level[u]+1;
 48             gap[level[v]]++;
 49             que.push(v);
 50         }
 51     }
 52 }
 53 
 54 int pre[MAXN],cur[MAXN];
 55 int SAP(int vs,int vt)
 56 {
 57     bfs(vt);
 58     memcpy(cur,head,sizeof(head));
 59     int u=pre[vs]=vs,aug=inf,maxflow=0;
 60     gap[0]=NV;
 61     while(level[vs]<NV){
 62         bool flag=false;
 63         for(int &i=cur[u];i!=-1;i=edge[i].next){
 64             int v=edge[i].v;
 65             if(edge[i].cap>0&&level[u]==level[v]+1){
 66                 flag=true;
 67                 aug=min(aug,edge[i].cap);
 68                 pre[v]=u;
 69                 u=v;
 70                 if(v==vt){
 71                     maxflow+=aug;
 72                     for(u=pre[u];v!=vs;v=u,u=pre[u]){
 73                         edge[cur[u]].cap-=aug;
 74                         edge[cur[u]^1].cap+=aug;
 75                     }
 76                     aug=inf;
 77                 }
 78                 break;
 79             }
 80         }
 81         if(flag)continue;
 82         int minlevel=NV;
 83         for(int i=head[u];i!=-1;i=edge[i].next){
 84             int v=edge[i].v;
 85             if(edge[i].cap>0&&level[v]<minlevel){
 86                 minlevel=level[v];
 87                 cur[u]=i;
 88             }
 89         }
 90         if(--gap[level[u]]==0)break;
 91         level[u]=minlevel+1;
 92         gap[level[u]]++;
 93         u=pre[u];
 94     }
 95     return maxflow;
 96 }
 97 
 98 int main()
 99 {
100     int _case,u,v,k1,k2,cap,t=1;
101     scanf("%d",&_case);
102     while(_case--){
103         scanf("%d",&n);
104         NE=0;
105         FILL(head,-1);
106         vs=0,vt=2*n+1,NV=vt+1;
107         for(int i=1;i<=n;i++)scanf("%d",&Cap[i]);
108         scanf("%d",&m);
109         while(m--){
110             scanf("%d%d%d",&u,&v,&cap);
111             Insert(u+n,v,cap);
112         }
113         for(int i=1;i<=n;i++)Insert(i,i+n,Cap[i]);
114         scanf("%d%d",&k1,&k2);
115         while(k1--){
116             scanf("%d",&u);
117             Insert(vs,u,inf);
118         }
119         while(k2--){
120             scanf("%d",&u);
121             Insert(u+n,vt,inf);
122         }
123         printf("Case %d: %d
",t++,SAP(vs,vt));
124     }
125     return 0;
126 }
View Code