hdu 4280比较裸的dinic算法

算法比较裸，不过要注意在hdu上递归层次多了是要暴栈的，所以看了别人的知道了外挂开栈这个东西避免暴栈，真心好用！

#include"stdio.h"

#include"string.h"

#pragma comment(linker, "/STACK:1024000000,1024000000")//外挂开栈

#define inf 99999999



int min(int a,int b)

{

    return a<b?a:b;

}



int e,head[100005];

int level[100005];

int q[100005];



struct node

{

    int to,val;

    int next;

}edge[200005];



void add_edge(int x,int y,int w)

{

    edge[e].to=y;

    edge[e].val=w;

    edge[e].next=head[x];

    head[x]=e++;



    edge[e].to=x;

    edge[e].val=w;

    edge[e].next=head[y];

    head[y]=e++;

}



bool bfs(int s,int t)

{

    int front=0,rear=0;

    int top,k;

    q[rear++]=s;

    memset(level,0,sizeof(level));

    level[s]=1;

    while(front<rear)

    {

        top=q[front++];

        if(top==t)

            return true;

        for(k=head[top];k!=-1;k=edge[k].next)

        {

            if(!level[edge[k].to]&&edge[k].val>0)

            {

                level[edge[k].to]=level[top]+1;

                q[rear++]=edge[k].to;

            }

        }

    }

    return false;

}



int dfs(int now,int maxf,int t)

{

    int ret=0,f,k;

    if(now==t)

        return maxf;

    for(k=head[now];k!=-1;k=edge[k].next)

    {

        if(level[edge[k].to]==level[now]+1&&edge[k].val>0)

        {

            f=dfs(edge[k].to,min(maxf-ret,edge[k].val),t);

            edge[k].val-=f;

            edge[k^1].val+=f;

            ret+=f;

            if(ret==maxf)

                return ret;

        }

    }

    if(ret==0)

        level[now]=0;

    return ret;

}



int dinic(int s,int t)

{

    int ans=0;

    while(bfs(s,t))

        ans+=dfs(s,inf,t);

    return ans;

}



int main( )

{

    int T,i,n,m,s,t;

    int x,y,w,ps,pt;

    scanf("%d",&T);

    while(T--)

    {

        e=0;s=inf;t=0;

        memset(head,-1,sizeof(head));

        scanf("%d%d",&n,&m);

        for(i=1;i<=n;i++)

        {

            scanf("%d%d",&x,&y);

            if(s>x)

            {s=x;ps=i;}

            if(t<x)

            {t=x;pt=i;}

        }            

        for(i=1;i<=m;i++)

        {

            scanf("%d%d%d",&x,&y,&w);

            add_edge(x,y,w);

        }

        printf("%d\n",dinic(ps,pt));

    }

    return 0;

}