Максимальный поток минимальной стоимости

#include <queue>
#include <vector>
#include <climits>
#include <iostream>
using namespace std;
 
typedef long long ll;
typedef pair<int, int> pii;
 
const int maxnodes = 200000;
 
int nodes = maxnodes;
int prio[maxnodes], curflow[maxnodes], prevedge[maxnodes], prevnode[maxnodes], q[maxnodes], pot[maxnodes];
bool inqueue[maxnodes];
 
struct Edge {
  int to, f, cap, cost, rev;
};
 
vector<Edge> graph[maxnodes];
 
void addEdge(int s, int t, int cap, int cost) {
  Edge a = {t, 0, cap, cost, graph[t].size()};
  Edge b = {s, 0, 0, -cost, graph[s].size()};
  graph[s].push_back(a);
  graph[t].push_back(b);
}
 
void bellmanFord(int s, int dist[]) {
  fill(dist, dist + nodes, INT_MAX);
  dist[s] = 0;
  int qt = 0;
  q[qt++] = s;
  for (int qh = 0; (qh - qt) % nodes != 0; qh++) {
    int u = q[qh % nodes];
    inqueue[u] = false;
    for (int i = 0; i < (int) graph[u].size(); i++) {
      Edge &e = graph[u][i];
      if (e.cap <= e.f) continue;
      int v = e.to;
      int ndist = dist[u] + e.cost;
      if (dist[v] > ndist) {
        dist[v] = ndist;
        if (!inqueue[v]) {
          inqueue[v] = true;
          q[qt++ % nodes] = v;
        }
      }
    }
  }
}
 
pii minCostFlow(int s, int t, int maxf) {
// bellmanFord can be safely commented if edges costs are non-negative
  bellmanFord(s, pot);
  int flow = 0;
  int flowCost = 0;
  while (flow < maxf) {
    priority_queue<ll, vector<ll>, greater<ll> > q;
    q.push(s);
    fill(prio, prio + nodes, INT_MAX);
    prio[s] = 0;
    curflow[s] = INT_MAX;
    while (!q.empty()) {
      ll cur = q.top();
      int d = cur >> 32;
      int u = cur;
      q.pop();
      if (d != prio[u])
        continue;
      for (int i = 0; i < (int) graph[u].size(); i++) {
        Edge &e = graph[u][i];
        int v = e.to;
        if (e.cap <= e.f) continue;
        int nprio = prio[u] + e.cost + pot[u] - pot[v];
        if (prio[v] > nprio) {
          prio[v] = nprio;
          q.push(((ll) nprio << 32) + v);
          prevnode[v] = u;
          prevedge[v] = i;
          curflow[v] = min(curflow[u], e.cap - e.f);
        }
      }
    }
    if (prio[t] == INT_MAX)
      break;
    for (int i = 0; i < nodes; i++)
      pot[i] += prio[i];
    int df = min(curflow[t], maxf - flow);
    flow += df;
    for (int v = t; v != s; v = prevnode[v]) {
      Edge &e = graph[prevnode[v]][prevedge[v]];
      e.f += df;
      graph[v][e.rev].f -= df;
      flowCost += df * e.cost;
    }
  }
  return make_pair(flow, flowCost);
}
 
// Usage example
 
int main() {
  int capacity[3][3] = {
    { 0, 3, 2},
    { 0, 0, 2},
    { 0, 0, 0}
  };
  nodes = 3;
  for (int i = 0; i < nodes; i++)
    for (int j = 0; j < nodes; j++)
      if (capacity[i][j] != 0)
        addEdge(i, j, capacity[i][j], 1);
  int s = 0;
  int t = 2;
  pii res = minCostFlow(s, t, INT_MAX);
  int flow = res.first;
  int flowCost = res.second;
  cout << (4 == flow) << endl;
  cout << (6 == flowCost) << endl;
}