Problem p02648 (C++)

Buggy submission (status: Runtime Error):
#pragma GCC target("sse,sse2,sse3,sse4,sse4.1,sse4.2,avx,avx2")
#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
#define all(x) x.begin(), x.end()

template <typename T1, typename T2> inline void chkmin(T1 &x, const T2 &y) {
  if (x > y)
    x = y;
}
template <typename T1, typename T2> inline void chkmax(T1 &x, const T2 &y) {
  if (x < y)
    x = y;
}

namespace fast {
/** Fast input-output */

template <class T = int> inline T readInt();
inline double readDouble();
inline int readUInt();
inline int readChar(); // first non-blank character
inline void readWord(char *s);
inline bool readLine(char *s); // do not save '\n'
inline bool isEof();
inline int getChar();
inline int peekChar();
inline bool seekEof();
inline void skipBlanks();

template <class T> inline void writeInt(T x, char end = 0, int len = -1);
inline void writeChar(int x);
inline void writeWord(const char *s);
inline void writeDouble(double x, int len = 0);
inline void flush();

static struct buffer_flusher_t {
  ~buffer_flusher_t() { flush(); }
} buffer_flusher;

/** Read */

static const int buf_size = 4096;

static unsigned char buf[buf_size];
static int buf_len = 0, buf_pos = 0;

inline bool isEof() {
  if (buf_pos == buf_len) {
    buf_pos = 0, buf_len = fread(buf, 1, buf_size, stdin);
    if (buf_pos == buf_len)
      return 1;
  }
  return 0;
}

inline int getChar() { return isEof() ? -1 : buf[buf_pos++]; }

inline int peekChar() { return isEof() ? -1 : buf[buf_pos]; }

inline bool seekEof() {
  int c;
  while ((c = peekChar()) != -1 && c <= 32)
    buf_pos++;
  return c == -1;
}

inline void skipBlanks() {
  while (!isEof() && buf[buf_pos] <= 32U)
    buf_pos++;
}

inline int readChar() {
  int c = getChar();
  while (c != -1 && c <= 32)
    c = getChar();
  return c;
}

inline int readUInt() {
  int c = readChar(), x = 0;
  while ('0' <= c && c <= '9')
    x = x * 10 + c - '0', c = getChar();
  return x;
}

template <class T> inline T readInt() {
  int s = 1, c = readChar();
  T x = 0;
  if (c == '-')
    s = -1, c = getChar();
  else if (c == '+')
    c = getChar();
  while ('0' <= c && c <= '9')
    x = x * 10 + c - '0', c = getChar();
  return s == 1 ? x : -x;
}

inline double readDouble() {
  int s = 1, c = readChar();
  double x = 0;
  if (c == '-')
    s = -1, c = getChar();
  while ('0' <= c && c <= '9')
    x = x * 10 + c - '0', c = getChar();
  if (c == '.') {
    c = getChar();
    double coef = 1;
    while ('0' <= c && c <= '9')
      x += (c - '0') * (coef *= 1e-1), c = getChar();
  }
  return s == 1 ? x : -x;
}

inline void readWord(char *s) {
  int c = readChar();
  while (c > 32)
    *s++ = c, c = getChar();
  *s = 0;
}

inline bool readLine(char *s) {
  int c = getChar();
  while (c != '\n' && c != -1)
    *s++ = c, c = getChar();
  *s = 0;
  return c != -1;
}

/** Write */

static int write_buf_pos = 0;
static char write_buf[buf_size];

inline void writeChar(int x) {
  if (write_buf_pos == buf_size)
    fwrite(write_buf, 1, buf_size, stdout), write_buf_pos = 0;
  write_buf[write_buf_pos++] = x;
}

inline void flush() {
  if (write_buf_pos) {
    fwrite(write_buf, 1, write_buf_pos, stdout), write_buf_pos = 0;
    fflush(stdout);
  }
}

template <class T> inline void writeInt(T x, char end, int output_len) {
  if (x < 0)
    writeChar('-'), x = -x;

  char s[24];
  int n = 0;
  while (x || !n)
    s[n++] = '0' + x % 10, x /= 10;
  while (n < output_len)
    s[n++] = '0';
  while (n--)
    writeChar(s[n]);
  if (end)
    writeChar(end);
}

inline void writeWord(const char *s) {
  while (*s)
    writeChar(*s++);
}

inline void writeDouble(double x, int output_len) {
  if (x < 0)
    writeChar('-'), x = -x;
  int t = (int)x;
  writeInt(t), x -= t;
  writeChar('.');
  for (int i = output_len - 1; i > 0; i--) {
    x *= 10;
    t = std::min(9, (int)x);
    writeChar('0' + t), x -= t;
  }
  x *= 10;
  t = std::min(9, (int)(x + 0.5));
  writeChar('0' + t);
}
} // namespace fast

using namespace fast;

const int MAXLOG = 18;
const int MAXN = ((1 << MAXLOG) + 228) * 10;
const int BUBEN = 12;
int n;
int v[MAXN], w[MAXN];

void read() {
  n = readInt();
  for (int i = 1; i <= n; ++i) {
    v[i] = readInt();
    w[i] = readInt();
  }
}

int getHeight(int v) {
  int ans = 0;
  while (v) {
    ans++;
    v /= 2;
  }
  return ans;
}

pair<int, int> fans[MAXN];
int topFans[MAXN];
int start[MAXN];
int revOrder[MAXN];

int have[MAXLOG];
int topHave;

void build(int v) {
  topHave = 0;
  while (v) {
    have[topHave++] = v;
    v /= 2;
  }
  reverse(have, have + topHave);
}

void precalc() {
  int pos = 0;
  for (int V = 0; V < n; ++V) {
    if (getHeight(V) != BUBEN)
      continue;
    revOrder[V] = pos;
    build(V);
    topFans[pos] = 0;
    if (pos > 0)
      start[pos] = start[pos - 1] + topFans[pos - 1];
    for (int mask = 0; mask < (1 << topHave); ++mask) {
      int sum = 0;
      int now = 0;
      for (int bit = 0; bit < topHave; ++bit) {
        if ((mask >> bit) & 1) {
          sum += w[have[bit]];
          now += v[have[bit]];
        }
      }
      fans[start[pos] + topFans[pos]++] = {sum, now};
    }
    sort(fans + start[pos], fans + start[pos] + topFans[pos]);
    for (int i = 1; i < topFans[pos]; ++i) {
      chkmax(fans[start[pos] + i].second, fans[start[pos] + i - 1].second);
    }
    ++pos;
  }
}

void stupid(int l) {
  int ans = 0;
  for (int mask = 0; mask < (1 << topHave); mask++) {
    int sum = 0;
    int now = 0;
    for (int bit = 0; bit < topHave; bit++) {
      if ((mask >> bit) & 1) {
        sum += w[have[bit]];
        now += v[have[bit]];
      }
      if (sum > l)
        break;
    }
    if (sum <= l) {
      chkmax(ans, now);
    }
  }
  writeInt(ans, '\n');
}

void smart(int l) {
  int szL = BUBEN;
  int szR = topHave - szL;
  int pos = revOrder[have[BUBEN - 1]];
  int ans = 0;
  for (int mask = 0; mask < (1 << szR); ++mask) {
    int sum = 0;
    int now = 0;
    for (int bit = 0; bit < szR; ++bit) {
      if ((mask >> bit) & 1) {
        sum += w[have[bit + szL]];
        now += v[have[bit + szL]];
      }
      if (sum > l)
        break;
    }
    if (sum > l)
      continue;
    chkmax(ans, now);
    int mypos = lower_bound(fans + start[pos], fans + start[pos] + topFans[pos],
                            make_pair(l - sum + 1, 0)) -
                fans - start[pos];
    mypos--;
    if (mypos >= 0 && mypos < topFans[pos]) {
      chkmax(ans, now + fans[start[pos] + mypos].second);
    }
  }
  writeInt(ans, '\n');
}

void solve() {
  int v, l;
  v = readInt();
  l = readInt();
  build(v);
  if (topHave <= BUBEN) {
    stupid(l);
  } else {
    smart(l);
  }
}

void run() {
  precalc();
  int q;
  q = readInt();
  while (q--) {
    solve();
  }
}

signed main() {
  read();
  run();
  return 0;
}

Fixed submission:
#pragma GCC target("sse,sse2,sse3,sse4,sse4.1,sse4.2,avx,avx2")
#include <bits/stdc++.h>

using namespace std;
using ll = long long;
using ull = unsigned long long;
using ld = long double;
#define all(x) x.begin(), x.end()

template <typename T1, typename T2> inline void chkmin(T1 &x, const T2 &y) {
  if (x > y)
    x = y;
}
template <typename T1, typename T2> inline void chkmax(T1 &x, const T2 &y) {
  if (x < y)
    x = y;
}

namespace fast {
/** Fast input-output */

template <class T = int> inline T readInt();
inline double readDouble();
inline int readUInt();
inline int readChar(); // first non-blank character
inline void readWord(char *s);
inline bool readLine(char *s); // do not save '\n'
inline bool isEof();
inline int getChar();
inline int peekChar();
inline bool seekEof();
inline void skipBlanks();

template <class T> inline void writeInt(T x, char end = 0, int len = -1);
inline void writeChar(int x);
inline void writeWord(const char *s);
inline void writeDouble(double x, int len = 0);
inline void flush();

static struct buffer_flusher_t {
  ~buffer_flusher_t() { flush(); }
} buffer_flusher;

/** Read */

static const int buf_size = 4096;

static unsigned char buf[buf_size];
static int buf_len = 0, buf_pos = 0;

inline bool isEof() {
  if (buf_pos == buf_len) {
    buf_pos = 0, buf_len = fread(buf, 1, buf_size, stdin);
    if (buf_pos == buf_len)
      return 1;
  }
  return 0;
}

inline int getChar() { return isEof() ? -1 : buf[buf_pos++]; }

inline int peekChar() { return isEof() ? -1 : buf[buf_pos]; }

inline bool seekEof() {
  int c;
  while ((c = peekChar()) != -1 && c <= 32)
    buf_pos++;
  return c == -1;
}

inline void skipBlanks() {
  while (!isEof() && buf[buf_pos] <= 32U)
    buf_pos++;
}

inline int readChar() {
  int c = getChar();
  while (c != -1 && c <= 32)
    c = getChar();
  return c;
}

inline int readUInt() {
  int c = readChar(), x = 0;
  while ('0' <= c && c <= '9')
    x = x * 10 + c - '0', c = getChar();
  return x;
}

template <class T> inline T readInt() {
  int s = 1, c = readChar();
  T x = 0;
  if (c == '-')
    s = -1, c = getChar();
  else if (c == '+')
    c = getChar();
  while ('0' <= c && c <= '9')
    x = x * 10 + c - '0', c = getChar();
  return s == 1 ? x : -x;
}

inline double readDouble() {
  int s = 1, c = readChar();
  double x = 0;
  if (c == '-')
    s = -1, c = getChar();
  while ('0' <= c && c <= '9')
    x = x * 10 + c - '0', c = getChar();
  if (c == '.') {
    c = getChar();
    double coef = 1;
    while ('0' <= c && c <= '9')
      x += (c - '0') * (coef *= 1e-1), c = getChar();
  }
  return s == 1 ? x : -x;
}

inline void readWord(char *s) {
  int c = readChar();
  while (c > 32)
    *s++ = c, c = getChar();
  *s = 0;
}

inline bool readLine(char *s) {
  int c = getChar();
  while (c != '\n' && c != -1)
    *s++ = c, c = getChar();
  *s = 0;
  return c != -1;
}

/** Write */

static int write_buf_pos = 0;
static char write_buf[buf_size];

inline void writeChar(int x) {
  if (write_buf_pos == buf_size)
    fwrite(write_buf, 1, buf_size, stdout), write_buf_pos = 0;
  write_buf[write_buf_pos++] = x;
}

inline void flush() {
  if (write_buf_pos) {
    fwrite(write_buf, 1, write_buf_pos, stdout), write_buf_pos = 0;
    fflush(stdout);
  }
}

template <class T> inline void writeInt(T x, char end, int output_len) {
  if (x < 0)
    writeChar('-'), x = -x;

  char s[24];
  int n = 0;
  while (x || !n)
    s[n++] = '0' + x % 10, x /= 10;
  while (n < output_len)
    s[n++] = '0';
  while (n--)
    writeChar(s[n]);
  if (end)
    writeChar(end);
}

inline void writeWord(const char *s) {
  while (*s)
    writeChar(*s++);
}

inline void writeDouble(double x, int output_len) {
  if (x < 0)
    writeChar('-'), x = -x;
  int t = (int)x;
  writeInt(t), x -= t;
  writeChar('.');
  for (int i = output_len - 1; i > 0; i--) {
    x *= 10;
    t = std::min(9, (int)x);
    writeChar('0' + t), x -= t;
  }
  x *= 10;
  t = std::min(9, (int)(x + 0.5));
  writeChar('0' + t);
}
} // namespace fast

using namespace fast;

const int MAXLOG = 18;
const int MAXN = ((1 << MAXLOG) + 228) * 50;
const int BUBEN = 12;
int n;
int v[MAXN], w[MAXN];

void read() {
  n = readInt();
  for (int i = 1; i <= n; ++i) {
    v[i] = readInt();
    w[i] = readInt();
  }
}

int getHeight(int v) {
  int ans = 0;
  while (v) {
    ans++;
    v /= 2;
  }
  return ans;
}

pair<int, int> fans[MAXN];
int topFans[MAXN];
int start[MAXN];
int revOrder[MAXN];

int have[MAXLOG];
int topHave;

void build(int v) {
  topHave = 0;
  while (v) {
    have[topHave++] = v;
    v /= 2;
  }
  reverse(have, have + topHave);
}

void precalc() {
  int pos = 0;
  for (int V = 0; V < n; ++V) {
    if (getHeight(V) != BUBEN)
      continue;
    revOrder[V] = pos;
    build(V);
    topFans[pos] = 0;
    if (pos > 0)
      start[pos] = start[pos - 1] + topFans[pos - 1];
    for (int mask = 0; mask < (1 << topHave); ++mask) {
      int sum = 0;
      int now = 0;
      for (int bit = 0; bit < topHave; ++bit) {
        if ((mask >> bit) & 1) {
          sum += w[have[bit]];
          now += v[have[bit]];
        }
      }
      fans[start[pos] + topFans[pos]++] = {sum, now};
    }
    sort(fans + start[pos], fans + start[pos] + topFans[pos]);
    for (int i = 1; i < topFans[pos]; ++i) {
      chkmax(fans[start[pos] + i].second, fans[start[pos] + i - 1].second);
    }
    ++pos;
  }
}

void stupid(int l) {
  int ans = 0;
  for (int mask = 0; mask < (1 << topHave); mask++) {
    int sum = 0;
    int now = 0;
    for (int bit = 0; bit < topHave; bit++) {
      if ((mask >> bit) & 1) {
        sum += w[have[bit]];
        now += v[have[bit]];
      }
      if (sum > l)
        break;
    }
    if (sum <= l) {
      chkmax(ans, now);
    }
  }
  writeInt(ans, '\n');
}

void smart(int l) {
  int szL = BUBEN;
  int szR = topHave - szL;
  int pos = revOrder[have[BUBEN - 1]];
  int ans = 0;
  for (int mask = 0; mask < (1 << szR); ++mask) {
    int sum = 0;
    int now = 0;
    for (int bit = 0; bit < szR; ++bit) {
      if ((mask >> bit) & 1) {
        sum += w[have[bit + szL]];
        now += v[have[bit + szL]];
      }
      if (sum > l)
        break;
    }
    if (sum > l)
      continue;
    chkmax(ans, now);
    int mypos = lower_bound(fans + start[pos], fans + start[pos] + topFans[pos],
                            make_pair(l - sum + 1, 0)) -
                fans - start[pos];
    mypos--;
    if (mypos >= 0 && mypos < topFans[pos]) {
      chkmax(ans, now + fans[start[pos] + mypos].second);
    }
  }
  writeInt(ans, '\n');
}

void solve() {
  int v, l;
  v = readInt();
  l = readInt();
  build(v);
  if (topHave <= BUBEN) {
    stupid(l);
  } else {
    smart(l);
  }
}

void run() {
  precalc();
  int q;
  q = readInt();
  while (q--) {
    solve();
  }
}

signed main() {
  read();
  run();
  return 0;
}