HDU 1532 Drainage Ditches(最大流)

最大流模版题,弄了好多天也没有明白..
今天好不容易根据记忆写了个..

/*  xzppp  */#include <iostream>#include <vector>#include <cstdio>#include <string.h>#include <algorithm>#include <queue>#include <map>#include <string>#include <cmath>#include <bitset>#include <iomanip>using namespace std;#define FFF freopen("in.txt","r",stdin);freopen("out.txt","w",stdout);#define lson l,m,rt<<1#define rson m+1,r,rt<<1|1#define MP make_pair#define PB push_backtypedef long long  LL;typedef unsigned long long ULL;typedef pair<int,int > pii;typedef pair<LL,LL> pll;typedef pair<double,double > pdd;typedef pair<double,int > pdi;const int MAXN = 1e5+17;const int MAXM = 1e6+17;const int MAXV = 2*1e3+17;const int BIT = 15+3;const int INF = 0x7fffffff;const LL INFF = 0x3f3f3f3f3f3f3f3f;const int MOD = 998244353;int vis[MAXN];struct edge{    int to,cap,rev;    edge(int a,int b,int c):to(a),cap(b),rev(c){};};vector<edge > G[MAXN];void adeg(int from,int to,int cap){    G[from].push_back(edge(to,cap,G[to].size()));    G[to].push_back(edge(from,0,G[from].size()-1));}int dfs(int p,int t,int f){    if(p==t) return f;    vis[p] = 1;    for (int i = 0; i < G[p].size(); ++i)    {        int next = G[p][i].to;        if(!vis[next]&&G[p][i].cap>0)        {            int d = dfs(next,t,min(G[p][i].cap,f));            if(d>0)            {                G[p][i].cap -= d;                G[next][G[p][i].rev].cap += d;                return d;            }        }    }    return 0;}int maxflow(int s,int t){    int res = 0;    while(1)    {        memset(vis, 0, sizeof(vis));        int f = dfs(s,t,INF);        if(f==0) return res;        res += f;    }}int main(){    #ifndef ONLINE_JUDGE     FFF    #endif    int m,n;    while(cin>>m>>n)    {        for (int i = 0; i < n; ++i)        {            G[i].clear();        }        for (int i = 0; i < m; ++i)        {            int u,v,c;            scanf("%d%d%d",&u,&v,&c);            u--;v--;            adeg(u, v, c);        }        int ans = maxflow(0, n-1);        cout<<ans<<endl;    }    return 0;}