最小费用最大流dinic

#include <algorithm>
#include <cstdio>
#include <cstring>
#include <queue>

const int N = 5e3 + 5, M = 1e5 + 5;
const int INF = 0x3f3f3f3f;
int n, m, tot = 1, lnk[N], cur[N], ter[M], nxt[M], cap[M], cost[M], dis[N], ret;
bool vis[N];

void add(int u, int v, int w, int c) {
  ter[++tot] = v, nxt[tot] = lnk[u], lnk[u] = tot, cap[tot] = w, cost[tot] = c;
}

void addedge(int u, int v, int w, int c) { add(u, v, w, c), add(v, u, 0, -c); }

bool spfa(int s, int t) {
  memset(dis, 0x3f, sizeof(dis));
  memcpy(cur, lnk, sizeof(lnk));
  std::queue<int> q;
  q.push(s), dis[s] = 0, vis[s] = 1;
  while (!q.empty()) {
    int u = q.front();
    q.pop(), vis[u] = 0;
    for (int i = lnk[u]; i; i = nxt[i]) {
      int v = ter[i];
      if (cap[i] && dis[v] > dis[u] + cost[i]) {
        dis[v] = dis[u] + cost[i];
        if (!vis[v]) q.push(v), vis[v] = 1;
      }
    }
  }
  return dis[t] != INF;
}

int dfs(int u, int t, int flow) {
  if (u == t) return flow;
  vis[u] = 1;
  int ans = 0;
  for (int &i = cur[u]; i && ans < flow; i = nxt[i]) {
    int v = ter[i];
    if (!vis[v] && cap[i] && dis[v] == dis[u] + cost[i]) {
      int x = dfs(v, t, std::min(cap[i], flow - ans));
      if (x) ret += x * cost[i], cap[i] -= x, cap[i ^ 1] += x, ans += x;
    }
  }
  vis[u] = 0;
  return ans;
}

int mcmf(int s, int t) {
  int ans = 0;
  while (spfa(s, t)) {
    int x;
    while ((x = dfs(s, t, INF))) ans += x;
  }
  return ans;
}

int main() {
  int s, t;
  scanf("%d%d%d%d", &n, &m, &s, &t);
  while (m--) {
    int u, v, w, c;
    scanf("%d%d%d%d", &u, &v, &w, &c);
    addedge(u, v, w, c);
  }
  int ans = mcmf(s, t);
  printf("%d %d\\n", ans, ret); // ans最大流， ret费用
  return 0;
}

最大流dinic


#define N 100005
#define INF 0x3f3f3f3f3f3f3f3f
using ll = long long;
struct MF {
    struct edge {
        int v, nxt;
        ll cap, flow;
    } e[N];

    int fir[N], cnt = 0;

    int n, S, T;
    ll maxflow = 0;
    int dep[N], cur[N];
  
    MF(int _n, int _s, int _t) {init(_n, _s, _t);}
  
    void init(int _n, int _s, int _t) {
        n = _n;
        S = _s;
        T = _t;
        memset(fir, -1, sizeof(int) * (n + 1));
        cnt = 0;
        maxflow = 0;
    }

    void addedge(int u, int v, int w) {
        e[cnt] = {v, fir[u], w, 0};
        fir[u] = cnt++;
        e[cnt] = {u, fir[v], 0, 0};
        fir[v] = cnt++;
    }

    bool bfs() {
        queue<int> q;
        memset(dep, 0, sizeof(int) * (n + 1));
        dep[S] = 1;
        q.push(S);
        while (q.size()) {
            int u = q.front();
            q.pop();
            for (int i = fir[u]; ~i; i = e[i].nxt) {
                int v = e[i].v;
                if ((!dep[v]) && (e[i].cap > e[i].flow)) {
                    dep[v] = dep[u] + 1;
                    q.push(v);
                }
            }
        }
        return dep[T];
    }

    ll dfs(int u, ll flow) {
        if ((u == T) || (!flow)) return flow;

        ll ret = 0, d;
        for (int& i = cur[u]; ~i; i = e[i].nxt) {
            int v = e[i].v;
            if ((dep[v] == dep[u] + 1) &&
                (d = dfs(v, min(flow - ret, e[i].cap - e[i].flow)))) {
                ret += d;
                e[i].flow += d;
                e[i ^ 1].flow -= d;
                if (ret == flow) return ret;
            }
        }
        return ret;
    }

    ll dinic() {
        while (bfs()) {
            memcpy(cur, fir, sizeof(int) * (n + 1));
            maxflow += dfs(S, INF);
        }
        return maxflow;
    }
};