最大流模板(ek和dinic)

EK

#include<iostream>
#include<cstring>
#include<cstdio>
#include<queue>
#include<cstdlib>
#include<cmath>
#include<stack>
#include<map>
#include<vector>
#include<algorithm>
using namespace std;
#define ll long long
#define INF 0x3f3f3f3f
const double pi = acos(-1);
const int maxn = 1e4 + 10;
const int maxm = 1e5 + 10;
const ll mod = 1e9 + 7;
int ans, cnt, m, n, s, t;
int head[maxn], vis[maxn];
struct node{
    int to;
    int next;
    int quan;
}edge[maxm << 1];
struct nod{
    int uu;
    int eg;
}pre[maxn];
void add(int u, int v, int w){
    edge[cnt].to = v;
    edge[cnt].quan = w;
    edge[cnt].next = head[u];
    head[u] = cnt ++;
}
bool bfs(){
    queue<int> que;
    memset(vis, 0, sizeof(vis));
    memset(pre, -1, sizeof(pre));
    vis[s] = 1;
    que.push(s);
    while(!que.empty()){
        int u = que.front();
        que.pop();
        for(int i = head[u] ; i != -1 ; i = edge[i].next){
            int v = edge[i].to;
            if(!vis[v] && edge[i].quan){
                pre[v].uu = u;
                pre[v].eg = i;
                if(v == t) return true;
                vis[v] = 1;
                que.push(v);
            }
        }
    }
    return false;
}
int main()
{
    int u, v, w;
    scanf("%d %d %d %d", &n, &m, &s, &t);
    memset(head, -1, sizeof(head));
    for(int i = 1 ; i <= m ; ++ i){
        scanf("%d %d %d", &u, &v, &w);
        add(u, v, w); add(v, u, 0);
    }
    while(bfs()){
        int mini = INF;
        for(int i = t ; i != s ; i = pre[i].uu){
            mini = min(mini, edge[pre[i].eg].quan);
        }
        for(int i = t ; i != s ; i = pre[i].uu){
            edge[pre[i].eg].quan -= mini;
            edge[pre[i].eg^1].quan += mini;
        }
        ans += mini;
    }
    printf("%d", ans);
    return 0;
}

Dinic

#include<iostream>
#include<cstring>
#include<cstdio>
#include<queue>
#include<cstdlib>
#include<cmath>
#include<stack>
#include<map>
#include<vector>
#include<algorithm>
using namespace std;
#define ll long long
#define INF 0x3f3f3f3f
#define endl '\n'
const double pi = acos(-1);
const int maxn = 5e4 + 10;
const int maxm = 5e5 + 10;
const ll mod = 1e9 + 7;
int n, m, s, t, cnt;
int head[maxn], vis[maxn], dep[maxn];
struct node{
    int to;
    int next;
    int quan;
}edge[maxm << 1];
void add(int u, int v, int w){
    edge[cnt].to = v;
    edge[cnt].quan = w;
    edge[cnt].next = head[u];
    head[u] = cnt ++;
}
int bfs(){
    memset(dep, INF, sizeof(dep));
    memset(vis, 0, sizeof(vis));
    queue<int> que;
    que.push(s);
    dep[s] = 0;
    vis[s] = 1;
    while(!que.empty()){
        int u = que.front();
        que.pop();
        vis[u] = 0;
        for(int i = head[u] ; i != -1 ; i = edge[i].next){
            int v = edge[i].to;
            if(dep[v] > dep[u] + 1 && edge[i].quan){
                dep[v] = dep[u] + 1;
                if(vis[v] == 0){
                    vis[v] = 1;
                    que.push(v);
                }
            }
        }
    }
    return dep[t] == INF ? 0 : 1;
}
int dfs(int u, int flow){
    int rlow = 0;
    if(u == t) return flow;
    for(int i = head[u] ; i != -1 ; i = edge[i].next){
        int v = edge[i].to;
        if(dep[v] == dep[u] + 1 && edge[i].quan){
            if(rlow = dfs(v, min(flow, edge[i].quan))){
                edge[i].quan -= rlow;
                edge[i^1].quan += rlow;
                return rlow;
            }
        }
    }
    return 0;
}
int dinic(){
    int lowflow = 0, maxflow = 0;
    while(bfs()){
        //puts("44");
        while(lowflow = dfs(s, INF)) maxflow += lowflow;
    }
    return maxflow;
}
int main()
{
    int u, v, w;
    scanf("%d %d %d %d", &n, &m, &s, &t);
    memset(head, -1, sizeof(head));
    for(int i = 1 ; i <= m ; ++ i){
        scanf("%d %d %d", &u, &v, &w);
        add(u, v, w); add(v, u, 0);
    }
    printf("%d", dinic());
    return 0;
}