POJ 1273 最水最水的网络最大流

来源：互联网发布：辣条属于淘宝哪个类目编辑：程序博客网时间：2024/06/18 17:53

直接最大流就可以了。没有任何困难，就是要注意数据范围，每组数据之后清零就可以了。

#include <iostream>#include <cstdio>#include <cstring>#include <queue>#include <algorithm>#include <vector>#define INF 0x7fffffff#define maxn 205#define maxm 300000using namespace std;int vis[maxn],cur[maxn],d[maxn],s,m,n,t;struct Edge{    int from,to,cap,flow;};vector<int>G[maxn];vector<Edge>edges;void init(){    for(int i=1;i<=n;i++)G[i].clear();    edges.clear();}void AddEdge(int from,int to,int cap){    edges.push_back((Edge){from,to,cap,0});    edges.push_back((Edge){to,from,0,0});    int m=edges.size();    G[from].push_back(m-2);    G[to].push_back(m-1);}bool BFS(){    memset(vis,0,sizeof vis);    queue<int>Q;    Q.push(s);    d[s]=0;    vis[s]=1;    while(!Q.empty())    {        int x = Q.front();Q.pop();        int len = G[x].size();        for(int i=0;i<len;i++)        {            Edge &e = edges[G[x][i]];            if(!vis[e.to]&&e.cap>e.flow)            {                vis[e.to]=1;                d[e.to]=d[x]+1;                Q.push(e.to);            }        }    }    return vis[t];}int DFS(int x ,int a){    if(x==t||a==0)return a;    int flow = 0,f;    int len = G[x].size();    for(int &i = cur[x];i<len ;i++)    {        Edge &e = edges[G[x][i]];        if(d[x]+1==d[e.to]&&(f=DFS(e.to,min(a,e.cap-e.flow)))>0)        {            e.flow+=f;            edges[G[x][i]^1].flow-=f;            flow+=f;            a-=f;            if(a==0)break;        }    }    return flow;}int Maxflow(int s ,int t){    int flow=0;    while(BFS())    {        memset(cur,0,sizeof cur);        flow+=DFS(s,INF);    }    return flow;}int main(){//    freopen("in.txt","r",stdin);    while(~scanf("%d%d",&m,&n))    {        init();        int u,v,w;        for(int i=0;i<m;i++)        {            scanf("%d%d%d",&u,&v,&w);            AddEdge(u,v,w);        }        s=1;t=n;        printf("%d\n",Maxflow(s,t));    }    return 0;}

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