Problem p02567 (C++)

Buggy submission (status: Runtime Error):
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define REP(i, n) for (int i = 0; i < n; i++)
#define REPR(i, n) for (int i = n - 1; i >= 0; i--)
#define FOR(i, m, n) for (int i = m; i < n; i++)
#define ALL(v) v.begin(), v.end()
#define SIZE(x) ll(x.size())
using P = pair<int, int>;
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
const int INF = 2e9;
const ll LINF = (1LL << 60);

template <class S, S (*op)(S, S), S (*e)()> struct segtree {
public:
  segtree() : segtree(0) {}
  segtree(int n) : segtree(vector<S>(n, e())) {}
  segtree(const vector<S> &v) : _n(int(v.size())) {
    log = 0;
    while ((1U << log) < (unsigned int)(_n))
      log++;
    size = 1 << log;
    d = vector<S>(2 * size, e());
    for (int i = 0; i < _n; i++)
      d[size + i] = v[i];
    for (int i = size - 1; i >= 1; i--)
      update(i);
  }

  void set(int p, S x) {
    assert(0 <= p && p < _n);
    p += size;
    d[p] = x;
    for (int i = 1; i <= log; i++)
      update(p >> i);
  }

  S get(int p) {
    assert(0 <= p && p < _n);
    return d[p + size];
  }

  S prod(int l, int r) {
    assert(0 <= l && l <= r && r <= _n);
    S sml = e(), smr = e();
    l += size;
    r += size;

    while (l < r) {
      if (l & 1)
        sml = op(sml, d[l++]);
      if (r & 1)
        smr = op(d[--r], smr);
      l >>= 1;
      r >>= 1;
    }
    return op(sml, smr);
  }

  S all_prod() { return d[1]; }

  template <bool (*f)(S)> int max_right(int l) {
    return max_right(l, [](S x) { return f(x); });
  }
  template <class F> int max_right(int l, F f) {
    assert(0 <= l && l <= _n);
    assert(f(e()));
    if (l == _n)
      return _n;
    l += size;
    S sm = e();
    do {
      while (l % 2 == 0)
        l >>= 1;
      if (!f(op(sm, d[l]))) {
        while (l < size) {
          l = (2 * l);
          if (f(op(sm, d[l]))) {
            sm = op(sm, d[l]);
            l++;
          }
        }
        return l - size;
      }
      sm = op(sm, d[l]);
      l++;
    } while ((l & -l) != l);
    return _n;
  }

  template <bool (*f)(S)> int min_left(int r) {
    return min_left(r, [](S x) { return f(x); });
  }
  template <class F> int min_left(int r, F f) {
    assert(0 <= r && r <= _n);
    assert(f(e()));
    if (r == 0)
      return 0;
    r += size;
    S sm = e();
    do {
      r--;
      while (r > 1 && (r % 2))
        r >>= 1;
      if (!f(op(d[r], sm))) {
        while (r < size) {
          r = (2 * r + 1);
          if (f(op(d[r], sm))) {
            sm = op(d[r], sm);
            r--;
          }
        }
        return r + 1 - size;
      }
      sm = op(d[r], sm);
    } while ((r & -r) != r);
    return 0;
  }

private:
  int _n, size, log;
  vector<S> d;

  void update(int k) { d[k] = op(d[2 * k], d[2 * k + 1]); }
};

int op(int a, int b) { return max(a, b); }

int e() { return 0; }

int target;

bool f(int v) { return v < target; }

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int n, q;
  cin >> n >> q;
  vector<int> a(n);
  REP(i, n) cin >> a[i];

  segtree<int, op, e> seg(a);

  while (q--) {
    int t;
    cin >> t;
    if (t == 1) {
      int x, v;
      cin >> x >> v;
      x--;
      seg.set(x, v);
    } else if (t == 2) {
      int l, r;
      cin >> l >> r;
      l--;
      cout << seg.prod(l, r) << '\n';
    } else {
      int x;
      cin >> x >> target;
      x--;
      cout << seg.max_right<f>(x) + 1 << '\n';
    }
  }

  return 0;
}


Fixed submission:
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define REP(i, n) for (int i = 0; i < n; i++)
#define REPR(i, n) for (int i = n - 1; i >= 0; i--)
#define FOR(i, m, n) for (int i = m; i < n; i++)
#define ALL(v) v.begin(), v.end()
#define SIZE(x) ll(x.size())
using P = pair<int, int>;
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return 1;
  }
  return 0;
}
template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return 1;
  }
  return 0;
}
const int INF = 2e9;
const ll LINF = (1LL << 60);

template <class S, S (*op)(S, S), S (*e)()> struct segtree {
public:
  segtree() : segtree(0) {}
  segtree(int n) : segtree(vector<S>(n, e())) {}
  segtree(const vector<S> &v) : _n(int(v.size())) {
    log = 0;
    while ((1U << log) < (unsigned int)(_n))
      log++;
    size = 1 << log;
    d = vector<S>(2 * size, e());
    for (int i = 0; i < _n; i++)
      d[size + i] = v[i];
    for (int i = size - 1; i >= 1; i--)
      update(i);
  }

  void set(int p, S x) {
    assert(0 <= p && p < _n);
    p += size;
    d[p] = x;
    for (int i = 1; i <= log; i++)
      update(p >> i);
  }

  S get(int p) {
    assert(0 <= p && p < _n);
    return d[p + size];
  }

  S prod(int l, int r) {
    assert(0 <= l && l <= r && r <= _n);
    S sml = e(), smr = e();
    l += size;
    r += size;

    while (l < r) {
      if (l & 1)
        sml = op(sml, d[l++]);
      if (r & 1)
        smr = op(d[--r], smr);
      l >>= 1;
      r >>= 1;
    }
    return op(sml, smr);
  }

  S all_prod() { return d[1]; }

  template <bool (*f)(S)> int max_right(int l) {
    return max_right(l, [](S x) { return f(x); });
  }
  template <class F> int max_right(int l, F f) {
    assert(0 <= l && l <= _n);
    assert(f(e()));
    if (l == _n)
      return _n;
    l += size;
    S sm = e();
    do {
      while (l % 2 == 0)
        l >>= 1;
      if (!f(op(sm, d[l]))) {
        while (l < size) {
          l = (2 * l);
          if (f(op(sm, d[l]))) {
            sm = op(sm, d[l]);
            l++;
          }
        }
        return l - size;
      }
      sm = op(sm, d[l]);
      l++;
    } while ((l & -l) != l);
    return _n;
  }

  template <bool (*f)(S)> int min_left(int r) {
    return min_left(r, [](S x) { return f(x); });
  }
  template <class F> int min_left(int r, F f) {
    assert(0 <= r && r <= _n);
    assert(f(e()));
    if (r == 0)
      return 0;
    r += size;
    S sm = e();
    do {
      r--;
      while (r > 1 && (r % 2))
        r >>= 1;
      if (!f(op(d[r], sm))) {
        while (r < size) {
          r = (2 * r + 1);
          if (f(op(d[r], sm))) {
            sm = op(d[r], sm);
            r--;
          }
        }
        return r + 1 - size;
      }
      sm = op(d[r], sm);
    } while ((r & -r) != r);
    return 0;
  }

private:
  int _n, size, log;
  vector<S> d;

  void update(int k) { d[k] = op(d[2 * k], d[2 * k + 1]); }
};

int op(int a, int b) { return max(a, b); }

int e() { return -1; }

int target;

bool f(int v) { return v < target; }

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int n, q;
  cin >> n >> q;
  vector<int> a(n);
  REP(i, n) cin >> a[i];

  segtree<int, op, e> seg(a);

  while (q--) {
    int t;
    cin >> t;
    if (t == 1) {
      int x, v;
      cin >> x >> v;
      x--;
      seg.set(x, v);
    } else if (t == 2) {
      int l, r;
      cin >> l >> r;
      l--;
      cout << seg.prod(l, r) << '\n';
    } else {
      int x;
      cin >> x >> target;
      x--;
      cout << seg.max_right<f>(x) + 1 << '\n';
    }
  }

  return 0;
}