Problem p02648 (C++) — buggy submission, verdict: 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>
#pragma GCC optimize("Ofast")
#pragma GCC target("avx")

using namespace std;

#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__)

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...);
}

struct IO {
#ifdef _WIN32
  inline char getchar_unlocked() { return getchar(); }
  inline void putchar_unlocked(char c) { putchar(c); }
#endif
  std::string separator = " ";
  template <class T> inline void read(T &x) {
    char c;
    do {
      c = getchar_unlocked();
    } while (c != '-' && (c < '0' || '9' < c));
    bool minus = 0;
    if (c == '-') {
      minus = 1;
      c = getchar_unlocked();
    }
    x = 0;
    while ('0' <= c && c <= '9') {
      x *= 10;
      x += c - '0';
      c = getchar_unlocked();
    }
    if (minus)
      x = -x;
  }
  inline void read(std::string &x) {
    char c;
    do {
      c = getchar_unlocked();
    } while (c == ' ' || c == '\\n');
    x.clear();
    do {
      x += c;
      c = getchar_unlocked();
    } while (c != ' ' && c != '\\n' && c != EOF);
  }
  template <class T> inline void read(std::vector<T> &v) {
    for (auto &x : v)
      read(x);
  }
  template <class S, class T> inline void read(std::pair<S, T> &p) {
    read(p.first);
    read(p.second);
  }
  template <class Head, class... Tail>
  inline void read(Head &head, Tail &...tail) {
    read(head);
    read(tail...);
  }
  template <class T> inline void write(T x) {
    char buf[32];
    int p = 0;
    if (x < 0) {
      x = -x;
      putchar_unlocked('-');
    }
    if (x == 0)
      putchar_unlocked('0');
    while (x > 0) {
      buf[p++] = (x % 10) + '0';
      x /= 10;
    }
    while (p) {
      putchar_unlocked(buf[--p]);
    }
  }
  inline void write(std::string x) {
    for (char c : x)
      putchar_unlocked(c);
  }
  inline void write(const char s[]) {
    for (int i = 0; s[i] != 0; ++i)
      putchar_unlocked(s[i]);
  }
  template <class T> inline void write(std::vector<T> v) {
    if (v.empty())
      return;
    for (auto itr = v.begin(); itr + 1 != v.end(); ++itr) {
      write(*itr);
      write(separator);
    }
    write(v.back());
  }
  template <class Head, class... Tail>
  inline void write(Head head, Tail... tail) {
    write(head);
    write(separator);
    write(tail...);
  }
  template <class Head, class... Tail>
  inline void writeln(Head head, Tail... tail) {
    write(head, tail...);
    write("\\n");
  }
  void set_separator(std::string s) { separator = s; }
} io;

constexpr int SZ = 100000;
constexpr int prs = 10;
ll pre[1 << prs][SZ + 1];

int main() {
  int N;
  cin >> N;
  vector<int> V(N + 1), W(N + 1);
  REP(i, N) cin >> V[i + 1] >> W[i + 1];
  FOR(i, 1, min(N + 1, 1 << prs)) {
    if (i != 1)
      copy(pre[i / 2], pre[i / 2] + SZ + 1, pre[i]);
    for (int j = SZ; j >= W[i]; --j)
      pre[i][j] = max(pre[i][j], pre[i][j - W[i]] + V[i]);
    REP(j, SZ) pre[i][j + 1] = max(pre[i][j + 1], pre[i][j]);
  }
  int Q;
  cin >> Q;
  while (Q--) {
    int v, L;
    cin >> v >> L;
    if (v < (1 << prs)) {
      cout << pre[v][L] << "\\n";
    } else {
      int bi = 32 - __builtin_clz(v) - prs;
      ll ans = 0;
      REP(b, 1 << bi) {
        int w = 0;
        ll va = 0;
        REP(i, bi) {
          if (bit(b, i)) {
            w += W[v >> i];
            va += V[v >> i];
          }
          if (w > L)
            break;
        }
        if (w <= L)
          ans = max(ans, pre[v >> bi][L - w] + va);
      }
      cout << ans << "\\n";
    }
  }
  return 0;
}


Error: TLE

Fixed submission:

#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
#pragma GCC target("avx")

using namespace std;

#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++)
using ll = long long;

constexpr int SZ = 100000;
constexpr int prs = 10;
ll pre[1 << prs][SZ + 1];

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  int N;
  cin >> N;
  vector<int> V(N + 1), W(N + 1);
  REP(i, N) cin >> V[i + 1] >> W[i + 1];
  FOR(i, 1, min(N + 1, 1 << prs)) {
    if (i != 1)
      copy(pre[i / 2], pre[i / 2] + SZ + 1, pre[i]);
    for (int j = SZ; j >= W[i]; --j)
      pre[i][j] = max(pre[i][j], pre[i][j - W[i]] + V[i]);
    REP(j, SZ) pre[i][j + 1] = max(pre[i][j + 1], pre[i][j]);
  }
  int Q;
  cin >> Q;
  while (Q--) {
    int v, L;
    cin >> v >> L;
    if (v < (1 << prs)) {
      cout << pre[v][L] << "\\n";
    } else {
      int lvl = 32 - __builtin_clz(v) - prs;
      ll ans = 0;
      REP(b, 1 << lvl) {
        int w = 0;
        ll va = 0;
        REP(i, lvl) {
          if ((b >> i) & 1) {
            w += W[v >> i];
            va += V[v >> i];
          }
          if (w > L)
            break;
        }
        if (w <= L)
          ans = max(ans, pre[v >> lvl][L - w] + va);
      }
      cout << ans << "\\n";
    }
  }
  return 0;
}