网络流模板

取自https://www.cnblogs.com/pk28/p/8039645.html

 基本不考虑ek了

#include<bits/stdc++.h>
using namespace std;
const int N=205;
const int inf=0x7fffffff;
int mp[N][N]; //残留网络，初始化为原图
bool visit[N];
int pre[N];
int m,n;
bool bfs(int s,int t)  //寻找一条从s到t的增广路，若找到返回true
{
    int p;
    queue<int > q;
    memset(pre,-1,sizeof(pre));
    memset(visit,false,sizeof(visit));
    pre[s]=s;
    visit[s]=true;
    q.push(s);
    while(!q.empty())
    {
        p=q.front();
        q.pop();
        for(int i=1;i<=n;i++)
        {
            if(mp[p][i]>0&&!visit[i])
            {
                pre[i]=p;
                visit[i]=true;
                if(i==t) return true;
                q.push(i);
            }
        }
    }
    return false;
}
int EdmondsKarp(int s,int t)
{
   int flow=0,d,i;
   while(bfs(s,t))
   {
       d=inf;
       for(i=t;i!=s;i=pre[i])
           d=d<mp[pre[i]][i]? d:mp[pre[i]][i];
       for(i=t;i!=s;i=pre[i])
       {
           mp[pre[i]][i]-=d;
           mp[i][pre[i]]+=d;
       }
       flow+=d;
   }
   return flow;
}

int main()
{
    while(scanf("%d%d",&m,&n)!=EOF)//m条路  n个点 1是原点 n是汇点
    {
        int u,v,w;
        memset(mp,0,sizeof(mp));
        for(int i=0;i<m;i++)
        {
            scanf("%d%d%d",&u,&v,&w);
            mp[u][v]+=w;
        }
        printf("%d
",EdmondsKarp(1,n));
    }
    return 0;
}

dinic

#include<cstring>
#include<cstdio>
#include<vector>
#include<queue>
#include<iostream>
using namespace std;
typedef long long ll;
const int INF = 0x3f3f3f3f;
const int N = 2000 ;
int p[N],s[N],e[N],v,c,k;

struct Edge {
  int from, to, cap, flow;
};

bool operator < (const Edge& a, const Edge& b) {
  return a.from < b.from || (a.from == b.from && a.to < b.to);
}

struct Dinic {
  int s,t;
  vector<Edge> edges;    // 边数的两倍
  vector<int> G[N];   // 邻接表，G[i][j]表示结点i的第j条边在e数组中的序号
  bool vis[N];        // BFS使用
  int d[N];           // 从起点到i的距离
  int cur[N];           // 当前弧指针

void init(int n) {
    for(int i = 0; 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});
    k = edges.size();
    G[from].push_back(k-2);
    G[to].push_back(k-1);
}

bool BFS() {
    memset(vis, 0, sizeof(vis));
    queue<int> Q;
    Q.push(s);
    vis[s] = 1;
    d[s] = 0;
    while(!Q.empty()) {
      int x = Q.front(); Q.pop();
      for(int i = 0; i < G[x].size(); 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;
    for(int& i = cur[x]; i < G[x].size(); 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) {
    this->s = s; this->t = t;
    int flow = 0;
    while(BFS()) {
      memset(cur, 0, sizeof(cur));
      flow += DFS(s, INF);
    }
    return flow;
  }
}g;

int main()
{

    int n,m;
    
    g.init(N);//一定要初始化!!!!



}