Problem p03159 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#define _USE_MATH_DEFINES
#include <complex>
#include <functional>
#include <math.h>
using namespace std;

#define rep(i, x) for (ll i = 0; i < x; i++)
#define repn(i, x) for (ll i = 1; i <= x; i++)

typedef long long ll;
const ll INF = 1e17;
const ll MOD = 1000000007;
const ll MAX = 4000001;
const double eps = 1E-18;

ll max(ll a, ll b) {
  if (a > b) {
    return a;
  }
  return b;
}

ll min(ll a, ll b) {
  if (a > b) {
    return b;
  }
  return a;
}

ll gcd(ll a, ll b) {
  if (b == 0) {
    return a;
  }
  if (a < b) {
    return gcd(b, a);
  }
  return gcd(b, a % b);
}

ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }

struct edge {
  ll ind;
  ll fr;
  ll to;
  ll d;
};

class mint {
  long long x;

public:
  mint(long long x = 0) : x((x % MOD + MOD) % MOD) {}
  mint operator-() const { return mint(-x); }
  mint &operator+=(const mint &a) {
    if ((x += a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator-=(const mint &a) {
    if ((x += MOD - a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator*=(const mint &a) {
    (x *= a.x) %= MOD;
    return *this;
  }
  mint operator+(const mint &a) const {
    mint res(*this);
    return res += a;
  }
  mint operator-(const mint &a) const {
    mint res(*this);
    return res -= a;
  }
  mint operator*(const mint &a) const {
    mint res(*this);
    return res *= a;
  }

  mint pow(ll t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }

  // for prime MOD
  mint inv() const { return pow(MOD - 2); }
  mint &operator/=(const mint &a) { return (*this) *= a.inv(); }
  mint operator/(const mint &a) const {
    mint res(*this);
    return res /= a;
  }

  friend ostream &operator<<(ostream &os, const mint &m) {
    os << m.x;
    return os;
  }
};

mint pw(mint a, ll b) {
  if (b == 0) {
    return 1;
  }
  mint ret = pw(a, b >> 1);
  ret *= ret;
  if (b & 1) {
    ret *= a;
  }
  return ret;
}

typedef vector<ll> vll;
typedef vector<vector<ll>> vvll;
typedef vector<vector<vector<ll>>> vvvll;

typedef vector<mint> vmint;
typedef vector<vector<mint>> vvmint;
typedef vector<vector<vector<mint>>> vvvmint;

//////////////////////////////////////
ll N;
vll A;
vvll g;

vvll mn;
vll dp1;
vll dp2;

vll merge(vll a, vll b) {
  // rep(i, a.size())cout << a[i] << " ";
  // cout << endl;
  // rep(i, b.size())cout << b[i] << " ";
  // cout << endl;

  vll c(a.size() + b.size() - 1, INF);
  rep(i, c.size()) {
    rep(j, b.size()) {
      if (i - j >= 0 && i - j < a.size())
        c[i] = min(c[i], a[i - j] + b[j]);
    }
  }

  return c;
}

void dfs(ll u, ll v) {
  mn[v].assign(1, A[v]);

  for (ll w : g[v]) {
    if (u == w) {
      continue;
    }
    dfs(v, w);

    vll b(mn[w].size() + 1, INF);
    rep(i, mn[w].size() + 1) {
      if (i < mn[w].size())
        b[i] = mn[w][i];
      if (i >= dp1[w] + 1) {
        b[i] = min(0, b[i]);
      }
    }
    mn[v] = merge(mn[v], b);
  }

  if (A[v] < 0) {
    dp1[v] = INF;
  } else {
    dp1[v] = 0;
    for (ll w : g[v]) {
      if (u == w) {
        continue;
      }
      dp1[v] += min(dp1[w], dp2[w] + 1);
    }
  }

  dp2[v] = INF;
  rep(i, mn[v].size()) {
    if (mn[v][i] < 0) {
      dp2[v] = i;
      break;
    }
  }

  // cout << v << " " << dp1[v] << " " << dp2[v] << endl;
  // for (ll x : mn[v]) { cout << x << " "; }
  // cout << endl;

  return;
}

int main() {
  cin >> N;
  A.assign(N + 1, 0);
  repn(i, N) cin >> A[i];

  g.resize(N + 1);
  repn(i, N - 1) {
    ll u, v;
    cin >> u >> v;
    g[u].push_back(v);
    g[v].push_back(u);
  }

  mn.resize(N + 1);
  dp1.resize(N + 1);
  dp2.resize(N + 1);

  dfs(0, 1);

  cout << min(dp1[1], dp2[1]) << endl;
}


Fixed submission:
#include <algorithm>
#include <cmath>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <stack>
#include <string>
#define _USE_MATH_DEFINES
#include <complex>
#include <functional>
#include <math.h>
using namespace std;

#define rep(i, x) for (ll i = 0; i < x; i++)
#define repn(i, x) for (ll i = 1; i <= x; i++)

typedef long long ll;
const ll INF = 1e17;
const ll MOD = 1000000007;
const ll MAX = 4000001;
const double eps = 1E-18;

ll max(ll a, ll b) {
  if (a > b) {
    return a;
  }
  return b;
}

ll min(ll a, ll b) {
  if (a > b) {
    return b;
  }
  return a;
}

ll gcd(ll a, ll b) {
  if (b == 0) {
    return a;
  }
  if (a < b) {
    return gcd(b, a);
  }
  return gcd(b, a % b);
}

ll lcm(ll a, ll b) { return a / gcd(a, b) * b; }

struct edge {
  ll ind;
  ll fr;
  ll to;
  ll d;
};

class mint {
  long long x;

public:
  mint(long long x = 0) : x((x % MOD + MOD) % MOD) {}
  mint operator-() const { return mint(-x); }
  mint &operator+=(const mint &a) {
    if ((x += a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator-=(const mint &a) {
    if ((x += MOD - a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator*=(const mint &a) {
    (x *= a.x) %= MOD;
    return *this;
  }
  mint operator+(const mint &a) const {
    mint res(*this);
    return res += a;
  }
  mint operator-(const mint &a) const {
    mint res(*this);
    return res -= a;
  }
  mint operator*(const mint &a) const {
    mint res(*this);
    return res *= a;
  }

  mint pow(ll t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }

  // for prime MOD
  mint inv() const { return pow(MOD - 2); }
  mint &operator/=(const mint &a) { return (*this) *= a.inv(); }
  mint operator/(const mint &a) const {
    mint res(*this);
    return res /= a;
  }

  friend ostream &operator<<(ostream &os, const mint &m) {
    os << m.x;
    return os;
  }
};

mint pw(mint a, ll b) {
  if (b == 0) {
    return 1;
  }
  mint ret = pw(a, b >> 1);
  ret *= ret;
  if (b & 1) {
    ret *= a;
  }
  return ret;
}

typedef vector<ll> vll;
typedef vector<vector<ll>> vvll;
typedef vector<vector<vector<ll>>> vvvll;

typedef vector<mint> vmint;
typedef vector<vector<mint>> vvmint;
typedef vector<vector<vector<mint>>> vvvmint;

//////////////////////////////////////
ll N;
vll A;
vvll g;

vvll mn;
vll dp1;
vll dp2;

vll merge(vll a, vll b) {
  // rep(i, a.size())cout << a[i] << " ";
  // cout << endl;
  // rep(i, b.size())cout << b[i] << " ";
  // cout << endl;

  vll c(a.size() + b.size() - 1, INF);
  rep(i, a.size()) rep(j, b.size()) { c[i + j] = min(c[i + j], a[i] + b[j]); }
  return c;
}

void dfs(ll u, ll v) {
  mn[v].assign(1, A[v]);

  for (ll w : g[v]) {
    if (u == w) {
      continue;
    }
    dfs(v, w);

    vll b(mn[w].size() + 1, INF);
    rep(i, mn[w].size() + 1) {
      if (i < mn[w].size())
        b[i] = mn[w][i];
      if (i >= dp1[w] + 1) {
        b[i] = min(0, b[i]);
      }
    }
    mn[v] = merge(mn[v], b);
  }

  if (A[v] < 0) {
    dp1[v] = INF;
  } else {
    dp1[v] = 0;
    for (ll w : g[v]) {
      if (u == w) {
        continue;
      }
      dp1[v] += min(dp1[w], dp2[w] + 1);
    }
  }

  dp2[v] = INF;
  rep(i, mn[v].size()) {
    if (mn[v][i] < 0) {
      dp2[v] = i;
      break;
    }
  }

  // cout << v << " " << dp1[v] << " " << dp2[v] << endl;
  // for (ll x : mn[v]) { cout << x << " "; }
  // cout << endl;

  return;
}

int main() {
  cin >> N;
  A.assign(N + 1, 0);
  repn(i, N) cin >> A[i];

  g.resize(N + 1);
  repn(i, N - 1) {
    ll u, v;
    cin >> u >> v;
    g[u].push_back(v);
    g[v].push_back(u);
  }

  mn.resize(N + 1);
  dp1.resize(N + 1);
  dp2.resize(N + 1);

  dfs(0, 1);

  cout << min(dp1[1], dp2[1]) << endl;
}