最大流 最小费用流模板

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
using namespace std;
const int INF = 0x3f3f3f3f;
const int N = 10005;
const int M = 100005;
struct type{
    int u, v, w, next;
}edge[M << 1];
int head[N], cnt;
int dep[N], cur[N];
int n, m, s, t, d;
void add(int x, int y, int z){
    edge[cnt].u = x;
    edge[cnt].v = y;
    edge[cnt].w = z;
    edge[cnt].next = head[x];
    head[x] = cnt;
    cnt++;
}
bool bfs(){
    int fro = 0;
    queue<int> q;
    q.push(s);
    for(int i = 1; i <= n; i++) dep[i] = 0;
    dep[s] = 1;//important!!!!!
    while(!q.empty()){
        fro = q.front(); q.pop();
        for(int i = head[fro]; i != -1; i = edge[i].next){
            int vv = edge[i].v;
            if(!dep[vv] && edge[i].w > 0){
                dep[vv] = dep[fro] + 1;
                q.push(vv);
            }
        }
    }
    return dep[t] ? 1 : 0;
}
int dfs(int x, int rest){
    if(x == t || !rest) return rest;
    for(int& i = cur[x]; i != -1; i = edge[i].next){//当前弧优化 
        int vv = edge[i].v, ww = edge[i].w;
        if(dep[vv] != dep[x] + 1) continue;
        d = dfs(vv, min(rest, ww));
        if(d > 0){
            edge[i].w -= d;
            edge[i ^ 1].w += d;
            return d;
        }
    }
    return 0;
}
int dinic(){
    int ans = 0;
    while(bfs()){
        for(int i = 1; i <= n; i++) cur[i] = head[i];//当前弧优化
        if(d = dfs(s, INF)){
            ans += d;
        }
    }
    return ans;
}
int main() {
    int x, y, z;
    scanf("%d%d%d%d", &n, &m, &s, &t);
    for(int i = 1; i <= n; i++) head[i] = -1;
    for(int i = 1; i <= m; i++){
        scanf("%d%d%d", &x, &y, &z);
        add(x, y, z);
        add(y, x, 0);
    }
    printf("%d", dinic());
    return 0;
}

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
using namespace std;
const int INF = 0x3f3f3f3f;
const int N = 5005;
const int M = 50005;
struct type{
    int u, v, w, f, next;
}edge[M << 1];
struct type2{
    int f, cur, incf;
    bool vis;
}ser[N];
int head[N], cnt;
int n, m, s, t;
int max_flow, min_cost;
void add(int x, int y, int z, int zz){
    edge[cnt].u = x;
    edge[cnt].v = y;
    edge[cnt].w = z;
    edge[cnt].f = zz;
    edge[cnt].next = head[x];
    head[x] = cnt;
    cnt++;
}
bool spfa(){
    for(int i = 1; i <= n; i++){
        ser[i].vis = 0;
        ser[i].f = INF;
    }
    ser[s].f = 0;
    ser[s].incf = INF;  
    int fro;
    queue<int> q;
    q.push(s);
    while(!q.empty()){
        fro = q.front(); q.pop(); ser[fro].vis = 0;
        for(int i = head[fro]; i != -1; i = edge[i].next){
            int vv = edge[i].v, ww = edge[i].w, ff = edge[i].f;
            if(ww > 0 && ser[fro].f + ff < ser[vv].f){
                ser[vv].f = ser[fro].f + ff;
                ser[vv].incf = min(ser[fro].incf, ww);
                ser[vv].cur = i;
                if(!ser[vv].vis){
                    ser[vv].vis = 1;
                    q.push(vv);
                }
            }
        }
    }
    return ser[t].f == INF ? 0 : 1;
}
void update(){
    int i = t, j;
    while(i != s){
        j = ser[i].cur;
        edge[j].w -= ser[t].incf;
        edge[j ^ 1].w += ser[t].incf;
        i = edge[j].u;
    }
    max_flow += ser[t].incf;
    min_cost += ser[t].f * ser[t].incf;
}
void EK(){
    while(spfa()){
        update();
    }
}
int main() {
    //freopen("testdata.in", "r", stdin);
    //freopen("testdata.out", "w", stdout);
    int x, y, z, zz;
    scanf("%d%d%d%d", &n, &m, &s, &t);
    for(int i = 1; i <= n; i++) head[i] = -1;
    for(int i = 1; i <= m; i++){
        scanf("%d%d%d%d", &x, &y, &z, &zz);
        add(x, y, z, zz);
        add(y, x, 0, -zz);
    }
    EK();
    printf("%d %d
", max_flow, min_cost);
    return 0;
}