HDU 3549 Flow Problem （简单最大流问题）

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题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=3549

简单明了的最大流问题，就当熟练模板了。

记得补题解的孩子都是好孩子。

#include <iostream>#include <cstdio>#include <cstring>#include <queue>#include <algorithm>#define MAX 65535#define Max 10000using namespace std;struct node{    int e;    int w;    int fro;}eg[Max << 1];int head[Max << 1];int cont;int add(int s,int e,int w){    eg[cont].e = e;    eg[cont].w = w;    eg[cont].fro = head[s];    head[s] = cont++;    eg[cont].e = s;    eg[cont].w = 0;    eg[cont].fro = head[e];    head[e] = cont++;    return 0;}int dis[Max << 1];int BFS(int s,int e){    queue<int> que;    int now;    memset(dis,-1,sizeof (dis));    dis[s] = 0;    que.push(s);    while (!que.empty())    {        now = que.front();        que.pop();        for (int i = head[now];i != -1;i = eg[i].fro)        {            int v = eg[i].e;            if (dis[v] == -1 && eg[i].w > 0)            {                dis[v] = dis[now] + 1;                que.push(v);            }        }    }    if (dis[e] != -1)        return 1;    return 0;}int dinic(int s,int e,int t){    if (s == e)        return t;    int tmp = t;    for (int i = head[s];i != -1;i = eg[i].fro)    {        int v = eg[i].e;        if (dis[v] == dis[s] +1 && eg[i].w > 0)        {            int imin = dinic(v,e,min(t,eg[i].w));            eg[i].w -= imin;            eg[i ^ 1].w += imin;            t -= imin;        }    }    return tmp - t;}int main(){    int n,m;    int N;    int cas = 1;    scanf ("%d",&N);    while (N--)    {        int i,k;        cont = 0;        memset(head,-1,sizeof (head));        scanf ("%d%d",&n,&m);        for (i = 0;i < m;i++)        {            int s,e,w;            scanf ("%d%d%d",&s,&e,&w);            add(s,e,w);        }        int ans = 0;        while (BFS(1,n))            ans += dinic(1,n,MAX);        printf ("Case %d: %d\n",cas++,ans);    }    return 0;}

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