HDU 1532 Drainage Ditches

来源：互联网发布：linux 计算文件夹大小编辑：程序博客网时间：2024/05/22 02:27
模板题。。。
//author: CHC  //First Edit Time:  2014-07-29 17:19  //Last Edit Time:   2014-08-03 08:52  #include <iostream>  #include <cstdio>  #include <cstring>  #include <cmath>  #include <set>  #include <vector>  #include <map>  #include <queue>  #include <set>  #include <algorithm>  #include <limits.h>  using namespace std;  #define MAXN 10000  #define MAXM 100000  const int INF = INT_MAX;  typedef long long LL;  struct Edge  {      int from,to,ci,next;      Edge(){}      Edge(int _from,int _to,int _ci,int _next):from(_from),to(_to),ci(_ci),next(_next){}  }e[MAXM];  int head[MAXN],tot;  int dis[MAXN];  int top,sta[MAXN],cur[MAXN];  int n,m;  inline void init(){      memset(head,-1,sizeof(head));      tot=0;  }  inline void AddEdge(int u,int v,int ci0,int ci1=0){      e[tot]=Edge(u,v,ci0,head[u]);      head[u]=tot++;      e[tot]=Edge(v,u,ci1,head[v]);      head[v]=tot++;  }  inline bool bfs(int st,int et){      memset(dis,0,sizeof(dis));      dis[st]=1;      queue <int> q;      q.push(st);      while(!q.empty()){          int now=q.front();          q.pop();          for(int i=head[now];i!=-1;i=e[i].next){              int next=e[i].to;              if(e[i].ci&&!dis[next]){                  dis[next]=dis[now]+1;                  if(next==et)return true;                  q.push(next);              }          }      }      return false;  }  LL Dinic(int st,int et){      LL ans=0;      while(bfs(st,et)){          top=0;          memcpy(cur,head,sizeof(head));          int u=st,i;          while(1){              if(u==et){                  int pos,minn=INF;                  //printf("top:%d\n",top);                  for(i=0;i<top;i++)                  {                      if(minn>e[sta[i]].ci){                          minn=e[sta[i]].ci;                          pos=i;                      }                      //printf("%d --> %d\n",e[sta[i]].from,e[sta[i]].to);                  }                  for(i=0;i<top;i++){                      e[sta[i]].ci-=minn;                      e[sta[i]^1].ci+=minn;                  }                  top=pos;                  u=e[sta[top]].from;                  ans+=minn;                  //printf("minn:%d\n\n",minn);              }              for(i=cur[u];i!=-1;cur[u]=i=e[i].next)                  if(e[i].ci&&dis[u]+1==dis[e[i].to])break;              if(cur[u]!=-1){                  sta[top++]=cur[u];                  u=e[cur[u]].to;              }              else {                  if(top==0)break;                  dis[u]=0;                  u=e[sta[--top]].from;              }          }      }      return ans;  }  int ru[MAXN],chu[MAXN];  int main() {      while(~scanf("%d%d",&m,&n)){          init();          for(int i=0,x,y,vi,ci;i<m;i++){              scanf("%d%d%d",&x,&y,&ci);              AddEdge(x,y,ci);              ru[y]++;              chu[x]++;          }          /*        int st,et;          for(int i=1;i<=n;i++){              if(ru[i]==0)st=i;              if(chu[i]==0)et=i;          }          */        printf("%I64d\n",Dinic(1,n));    }      return 0;  }
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