Airport

// clang-format off
#include <bits/stdc++.h>
#include <optional>
using namespace std;
#ifdef DO_DBG
template<typename A, typename B> ostream& operator<<(ostream &os, const pair<A, B> &p) { return os << '(' << p.first << ", " << p.second << ')'; }
template<typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type> ostream& operator<<(ostream &os, const T_container &v) { os << '{'; string sep; for (const T &x : v) os << sep << x, sep = ", "; return os << '}'; }
void dbg_out() { cerr << endl; }
template<typename Head, typename... Tail> void dbg_out(Head H, Tail... T) { cerr << ' ' << H; dbg_out(T...); }
#define dbg(...) cerr << "(" << #__VA_ARGS__ << "):", dbg_out(__VA_ARGS__)
#define dout cerr
#define debug true
#else
#define dbg(...)
#define dout if (0) cerr
#define debug false
#endif
typedef long long ll; typedef unsigned long long ull; typedef long double ld;
template <typename T> using v = vector<T>; template <typename T> using us = unordered_set<T>; template <typename K, typename V> using p = pair<K,V>;
template <typename K, typename V> using um = unordered_map<K, V>; template <typename K, typename V> using p = pair<K, V>;
template <typename T> using pq = priority_queue<T>; template <typename T> using nl = numeric_limits<T>; template <typename T> using il = initializer_list<T>;
constexpr int MOD = 1e9 + 7; constexpr int INF = 1e9; constexpr ld EPS = 1e-9;
#define fr(i,a,b) for (size_t i = a; i < b; i++)
#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL); cin.exceptions(cin.failbit);
#define frr(i,a,b) for (size_t i = b-1; i >= a; i--)
#define frs(i,a,b) for (ll i = a; i < b; i++)
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
#define sq(x) ((x) * (x))
template <typename... Args> void read(Args&... args) { ((cin >> args), ...); }
#define d(...) int __VA_ARGS__; read(__VA_ARGS__);
#define dll(...) ll __VA_ARGS__; read(__VA_ARGS__);
#define dv(x, n) vector<int> x(n); for (int i = 0; i < n; i++) cin >> x[i];
#define dvll(x, n) vector<long long> x(n); for (int i = 0; i < n; i++) cin >> x[i];
#define dvd(x, n) vector<double> x(n); for (int i = 0; i < n; i++) cin >> x[i];
ll ipow(ll a,int b){ll r=1;for(;b;b>>=1,a*=a)if(b&1)r*=a;return r;}
template<class F>struct y_combinator{F f;template<class...Args>decltype(auto)operator()(Args&&...args)const{return f(*this,forward<Args>(args)...);}};
constexpr auto get_nums=[]<typename T>(T&&s){istringstream iss(forward<T>(s));return vector<int>{istream_iterator<int>{iss},{}};};
// clang-format on

struct edge {
  ll to, w;
  size_t rev;
};

constexpr auto inf = nl<ll>::max();

int main() {
  fastio;
  dll(n, m);
  dvll(r, n);
  for (auto &r1 : r) {
    if (r1 == -1)
      r1 = inf;
  }

  v<v<edge>> adj(2 * n); // first half is in, second half is out
  ll threshold = inf;
  while (m--) {
    dll(a, b);
    a--;
    b--;
    // corridor goes from a to b
    // or, from a_out to b_in
    // and reverse is from b_in to a_out
    adj[a + n].push_back({b, inf, adj[b].size()});
    adj[b].push_back({a + n, 0, adj[a + n].size() - 1});
  }
  frs(i, 0, n) {
    // from i_in to i_out
    adj[i].push_back({i + n, r[i], adj[i + n].size()});
    // reverse
    adj[i + n].push_back({i, 0, adj[i].size() - 1});
  }

  ll found_min_w = 0;
  ll total_flow = 0;
  do {
    v<bool> vis(2 * n);
    // if we just want to calculate min_w we could do bottom up
    // but since we want to know the min_flow before bubbling up
    // (because we want to decrease w) we pass the flow from the top
    // to the bottom
    // this also allows us to simplify the base case a bit, since we can recurse
    // into the last node

    found_min_w = y_combinator([&](auto dfs, ll node, ll flow_td) -> ll {
      if (node == n - 1)
        return flow_td;
      vis[node] = true;
      for (auto &[c, w, rev] : adj[node]) {
        if (w >= threshold && !vis[c]) {
          auto new_flow = dfs(c, min(w, flow_td));
          if (new_flow) {
            // we found a path
            // we know new_flow is the minimum weight, since
            // w was considered for each edge when recursing top down
            w -= new_flow;
            // increment the reverse edge
            // find_if(all(adj[c]), [node](auto &p) {
            //   return p.first == node;
            // })->second += new_flow;
            adj[c][rev].w += new_flow;
            return new_flow;
          }
        }
      }
      return 0;
    })(0, inf);
    total_flow += found_min_w;
    if (!found_min_w)
      threshold /= 2;
    // scaling algorithm ^
  } while (threshold);

  cout << total_flow << "\n";
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED