Problem p02648 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <deque>
#include <functional>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>

#define REP(i, N) for (int i = 0; i < (int)N; i++)
#define FOR(i, a, b) for (int i = a; i < (int)b; i++)
#define ALL(x) (x).begin(), (x).end()
#define INF (1 << 30)
#define LLINF (1LL << 62)
#define DEBUG(...) debug(__LINE__, ":" __VA_ARGS__)

using namespace std;

constexpr int MOD = 1000000007;
using ll = long long;
using Pii = pair<int, int>;
using Pll = pair<ll, ll>;

inline int popcount(ll x) { return __builtin_popcountll(x); }
inline int div2num(ll x) { return __builtin_ctzll(x); }
inline bool bit(ll x, int b) { return (x >> b) & 1; }

template <class T> string to_string(T s);
template <class S, class T> string to_string(pair<S, T> p);
string to_string(string s) { return s; }
string to_string(const char s[]) { return to_string(string(s)); }

template <class T> string to_string(T v) {
  if (v.empty())
    return "{}";
  string ret = "{";
  for (auto x : v)
    ret += to_string(x) + ",";
  ret.back() = '}';
  return ret;
}

template <class S, class T> string to_string(pair<S, T> p) {
  return "{" + to_string(p.first) + ":" + to_string(p.second) + "}";
}
void debug() { cerr << endl; }

template <class Head, class... Tail> void debug(Head head, Tail... tail) {
  cerr << to_string(head) << " ";
  debug(tail...);
}

int main() {
  int N;
  cin >> N;
  vector<int> V(N + 1), W(N + 1);
  REP(i, N) cin >> V[i + 1] >> W[i + 1];
  int Q;
  cin >> Q;
  constexpr int b = 2;
  vector<pair<int, int>> l1, l2, tmp;
  while (Q--) {
    int v, L;
    cin >> v >> L;
    l1.clear();
    l2.clear();
    auto gen = [&](vector<pair<int, int>> &l, int thr) {
      l.emplace_back(0, 0);
      while (v >= thr) {
        int p1 = 0, p2 = 0;
        while (p1 < l.size() || p2 < l.size()) {
          if (p1 < l.size() && l[p1].first < l[p2].first + W[v]) {
            if (tmp.empty() || tmp.back().second < l[p1].second)
              tmp.emplace_back(l[p1]);
            p1++;
          } else {
            if (tmp.empty() || tmp.back().second < l[p2].second + V[v])
              tmp.emplace_back(l[p2].first + W[v], l[p2].second + V[v]);
            p2++;
          }
        }
        v /= 2;
        swap(l, tmp);
        tmp.clear();
      }
    };
    gen(l1, 1 << b);
    gen(l2, 1);
    int p1 = 0, p2 = 0;
    while (p2 + 1 < l2.size() && l1[p1].first + l2[p2 + 1].first <= L)
      p2++;
    int ans = l1[p1].second + l2[p2].second;
    while (++p1 < l1.size() && l1[p1].first <= L) {
      while (l1[p1].first + l2[p2].first > L)
        p2--;
      ans = max(ans, l1[p1].second + l2[p2].second);
    }
    cout << ans << "\n";
  }
  return 0;
}


Fixed submission:
#include <algorithm>
#include <bitset>
#include <cassert>
#include <cmath>
#include <cstdio>
#include <deque>
#include <functional>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>

#define REP(i, N) for (int i = 0; i < (int)N; i++)
#define FOR(i, a, b) for (int i = a; i < (int)b; i++)
#define ALL(x) (x).begin(), (x).end()
#define INF (1 << 30)
#define LLINF (1LL << 62)
#define DEBUG(...) debug(__LINE__, ":" __VA_ARGS__)

using namespace std;

constexpr int MOD = 1000000007;
using ll = long long;
using Pii = pair<int, int>;
using Pll = pair<ll, ll>;

inline int popcount(ll x) { return __builtin_popcountll(x); }
inline int div2num(ll x) { return __builtin_ctzll(x); }
inline bool bit(ll x, int b) { return (x >> b) & 1; }

template <class T> string to_string(T s);
template <class S, class T> string to_string(pair<S, T> p);
string to_string(string s) { return s; }
string to_string(const char s[]) { return to_string(string(s)); }

template <class T> string to_string(T v) {
  if (v.empty())
    return "{}";
  string ret = "{";
  for (auto x : v)
    ret += to_string(x) + ",";
  ret.back() = '}';
  return ret;
}

template <class S, class T> string to_string(pair<S, T> p) {
  return "{" + to_string(p.first) + ":" + to_string(p.second) + "}";
}
void debug() { cerr << endl; }

template <class Head, class... Tail> void debug(Head head, Tail... tail) {
  cerr << to_string(head) << " ";
  debug(tail...);
}

int main() {
  int N;
  cin >> N;
  vector<int> V(N + 1), W(N + 1);
  REP(i, N) cin >> V[i + 1] >> W[i + 1];
  int Q;
  cin >> Q;
  constexpr int b = 9;
  vector<pair<int, int>> l1, l2, tmp;
  while (Q--) {
    int v, L;
    cin >> v >> L;
    l1.clear();
    l2.clear();
    auto gen = [&](vector<pair<int, int>> &l, int thr) {
      l.emplace_back(0, 0);
      while (v >= thr) {
        int p1 = 0, p2 = 0;
        while (p1 < l.size() || p2 < l.size()) {
          if (p1 < l.size() && l[p1].first < l[p2].first + W[v]) {
            if (tmp.empty() || tmp.back().second < l[p1].second)
              tmp.emplace_back(l[p1]);
            p1++;
          } else {
            if (tmp.empty() || tmp.back().second < l[p2].second + V[v])
              tmp.emplace_back(l[p2].first + W[v], l[p2].second + V[v]);
            p2++;
          }
        }
        v /= 2;
        swap(l, tmp);
        tmp.clear();
      }
    };
    gen(l1, 1 << b);
    gen(l2, 1);
    int p1 = 0, p2 = 0;
    while (p2 + 1 < l2.size() && l1[p1].first + l2[p2 + 1].first <= L)
      p2++;
    int ans = l1[p1].second + l2[p2].second;
    while (++p1 < l1.size() && l1[p1].first <= L) {
      while (l1[p1].first + l2[p2].first > L)
        p2--;
      ans = max(ans, l1[p1].second + l2[p2].second);
    }
    cout << ans << "\n";
  }
  return 0;
}