网络流SAP--模板 

  1 #include<stdio.h>
  2 #include<iostream>
  3 #include<algorithm>
  4 using namespace std;
  5 typedef  struct {int v,next,val;} edge;
  6 const int MAXN=20010;
  7 const int MAXM=500010;
  8 edge e[MAXM];
  9 int p[MAXN],eid;
 10 inline void init(){memset(p,-1,sizeof(p));eid=0;}
 11 //有向
 12 inline void insert1(int from,int to,int val)
 13 {
 14     e[eid].v=to;
 15     e[eid].val=val;
 16     e[eid].next=p[from];
 17     p[from]=eid++;
 18     swap(from,to);
 19     e[eid].v=to;
 20     e[eid].val=0;
 21     e[eid].next=p[from];
 22     p[from]=eid++;
 23 }
 24 //无向
 25 inline void insert2(int from,int to,int val)
 26 {
 27     e[eid].v=to;
 28     e[eid].val=val;
 29     e[eid].next=p[from];
 30     p[from]=eid++;
 31     swap(from,to);
 32     e[eid].v=to;
 33     e[eid].val=val;
 34     e[eid].next=p[from];
 35     p[from]=eid++;
 36 }
 37 int n,m;//n为点数 m为边数
 38 int h[MAXN];
 39 int gap[MAXN];
 40 int source,sink;
 41 inline int dfs(int pos,int cost)
 42 {
 43     if (pos==sink)
 44     {
 45         return cost;
 46     }
 47     int j,minh=n-1,lv=cost,d;
 48     for (j=p[pos];j!=-1;j=e[j].next)
 49     {
 50         int v=e[j].v,val=e[j].val;
 51         if(val>0)
 52         {
 53             if (h[v]+1==h[pos])
 54             {
 55                 if (lv<e[j].val) d=lv;
 56                 else d=e[j].val;
 57                 
 58                 d=dfs(v,d);
 59                 e[j].val-=d;
 60                 e[j^1].val+=d;
 61                 lv-=d;
 62                 if (h[source]>=n) return cost-lv;
 63                 if (lv==0) break;
 64             }
 65             if (h[v]<minh)    minh=h[v];
 66         }
 67     }
 68     if (lv==cost)
 69     {
 70         --gap[h[pos]];
 71         if (gap[h[pos]]==0) h[source]=n;
 72         h[pos]=minh+1;
 73         ++gap[h[pos]];
 74     }
 75     return cost-lv;
 76 }
 77 int sap(int st,int ed)
 78 {
 79     source=st;
 80     sink=ed;
 81     int ret=0;
 82     memset(gap,0,sizeof(gap));
 83     memset(h,0,sizeof(h));
 84     gap[st]=n;
 85     while (h[st]<n)
 86     {
 87         ret+=dfs(st,INT_MAX);
 88     }
 89     return ret;
 90 }
 91 int main()
 92 {
 93     int t,add=1;
 94     scanf("%d",&t);
 95     while(t--)
 96     {
 97         printf("Case %d: ",add++);
 98         scanf("%d%d",&n,&m);
 99         init();
100         int i;
101         int ll,rr,cap;
102         for(i=0;i<m;i++)
103         {
104             scanf("%d%d%d",&ll,&rr,&cap);
105             insert1(ll,rr,cap);
106         }
107         printf("%d\n",sap(1,n));
108     }
109     return 0;
110 }

posted on 2012-08-13 21:38  acoderworld  阅读(286)  评论(0)    收藏  举报

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