Problem p02763 (C++)

Buggy submission (status: Runtime Error):
// #define _GLIBCXX_DEBUG
// #include <atcoder/all>
#include <bits/stdc++.h>

#ifndef ATCODER_INTERNAL_TYPE_TRAITS_HPP
#define ATCODER_INTERNAL_TYPE_TRAITS_HPP 1

#include <cassert>
#include <numeric>
#include <type_traits>

namespace atcoder {

namespace internal {

#ifndef _MSC_VER
template <class T>
using is_signed_int128 =
    typename std::conditional<std::is_same<T, __int128_t>::value ||
                                  std::is_same<T, __int128>::value,
                              std::true_type, std::false_type>::type;

template <class T>
using is_unsigned_int128 =
    typename std::conditional<std::is_same<T, __uint128_t>::value ||
                                  std::is_same<T, unsigned __int128>::value,
                              std::true_type, std::false_type>::type;

template <class T>
using make_unsigned_int128 =
    typename std::conditional<std::is_same<T, __int128_t>::value, __uint128_t,
                              unsigned __int128>;

template <class T>
using is_integral =
    typename std::conditional<std::is_integral<T>::value ||
                                  is_signed_int128<T>::value ||
                                  is_unsigned_int128<T>::value,
                              std::true_type, std::false_type>::type;

template <class T>
using is_signed_int =
    typename std::conditional<(is_integral<T>::value &&
                               std::is_signed<T>::value) ||
                                  is_signed_int128<T>::value,
                              std::true_type, std::false_type>::type;

template <class T>
using is_unsigned_int =
    typename std::conditional<(is_integral<T>::value &&
                               std::is_unsigned<T>::value) ||
                                  is_unsigned_int128<T>::value,
                              std::true_type, std::false_type>::type;

template <class T>
using to_unsigned = typename std::conditional<
    is_signed_int128<T>::value, make_unsigned_int128<T>,
    typename std::conditional<std::is_signed<T>::value, std::make_unsigned<T>,
                              std::common_type<T>>::type>::type;

#else

template <class T> using is_integral = typename std::is_integral<T>;

template <class T>
using is_signed_int =
    typename std::conditional<is_integral<T>::value && std::is_signed<T>::value,
                              std::true_type, std::false_type>::type;

template <class T>
using is_unsigned_int =
    typename std::conditional<is_integral<T>::value &&
                                  std::is_unsigned<T>::value,
                              std::true_type, std::false_type>::type;

template <class T>
using to_unsigned =
    typename std::conditional<is_signed_int<T>::value, std::make_unsigned<T>,
                              std::common_type<T>>::type;

#endif

template <class T>
using is_signed_int_t = std::enable_if_t<is_signed_int<T>::value>;

template <class T>
using is_unsigned_int_t = std::enable_if_t<is_unsigned_int<T>::value>;

template <class T> using to_unsigned_t = typename to_unsigned<T>::type;

} // namespace internal

} // namespace atcoder

#endif // ATCODER_INTERNAL_TYPE_TRAITS_HPP

#ifndef ATCODER_FENWICKTREE_HPP
#define ATCODER_FENWICKTREE_HPP 1

#include <cassert>
#include <vector>

namespace atcoder {

// Reference: https://en.wikipedia.org/wiki/Fenwick_tree
template <class T> struct fenwick_tree {
  using U = internal::to_unsigned_t<T>;

public:
  fenwick_tree() : _n(0) {}
  fenwick_tree(int n) : _n(n), data(n) {}

  void add(int p, T x) {
    assert(0 <= p && p < _n);
    p++;
    while (p <= _n) {
      data[p - 1] += U(x);
      p += p & -p;
    }
  }

  T sum(int l, int r) {
    assert(0 <= l && l <= r && r <= _n);
    return sum(r) - sum(l);
  }

private:
  int _n;
  std::vector<U> data;

  U sum(int r) {
    U s = 0;
    while (r > 0) {
      s += data[r - 1];
      r -= r & -r;
    }
    return s;
  }
};

} // namespace atcoder

#endif // ATCODER_FENWICKTREE_HPP

using namespace std;
using namespace atcoder;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
using ll = long long;
const ll MOD = 1000000007;
// const ll MOD=998244353;
const long long INF = 1LL << 60;
const double pi = acos(-1.0);
int dx[9] = {1, 0, -1, 0, 1, 1, -1, -1, 0};
int dy[9] = {0, 1, 0, -1, 1, -1, -1, 1, 0};

template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  // cout << fixed << setprecision(15);

  ll N, Q;
  cin >> N;
  string S;
  cin >> S;
  cin >> Q;

  vector<fenwick_tree<int>> fw_vec(26, fenwick_tree<int>(N));
  rep(i, N) {
    ll c = S[i] - 'a';
    fw_vec[c].add(i, 1);
  }
  rep(i, Q) {
    int t;
    cin >> t;
    if (t == 1) {
      ll j;
      char chnc;
      cin >> j >> chnc;
      j--;
      ll c = S[i] - 'a';
      S[i] = chnc;
      ll nc = chnc - 'a';
      fw_vec[c].add(j, -1);
      fw_vec[nc].add(j, 1);
    } else {
      ll l, r;
      cin >> l >> r;
      l--;
      r--;
      ll ans = 0;
      rep(j, 26) {
        if (fw_vec[j].sum(l, r + 1))
          ans++;
      }
      cout << ans << '\n';
    }
  }

  return 0;
}


Fixed submission:
// #define _GLIBCXX_DEBUG
// #include <atcoder/all>
#include <bits/stdc++.h>

#ifndef ATCODER_INTERNAL_TYPE_TRAITS_HPP
#define ATCODER_INTERNAL_TYPE_TRAITS_HPP 1

#include <cassert>
#include <numeric>
#include <type_traits>

namespace atcoder {

namespace internal {

#ifndef _MSC_VER
template <class T>
using is_signed_int128 =
    typename std::conditional<std::is_same<T, __int128_t>::value ||
                                  std::is_same<T, __int128>::value,
                              std::true_type, std::false_type>::type;

template <class T>
using is_unsigned_int128 =
    typename std::conditional<std::is_same<T, __uint128_t>::value ||
                                  std::is_same<T, unsigned __int128>::value,
                              std::true_type, std::false_type>::type;

template <class T>
using make_unsigned_int128 =
    typename std::conditional<std::is_same<T, __int128_t>::value, __uint128_t,
                              unsigned __int128>;

template <class T>
using is_integral =
    typename std::conditional<std::is_integral<T>::value ||
                                  is_signed_int128<T>::value ||
                                  is_unsigned_int128<T>::value,
                              std::true_type, std::false_type>::type;

template <class T>
using is_signed_int =
    typename std::conditional<(is_integral<T>::value &&
                               std::is_signed<T>::value) ||
                                  is_signed_int128<T>::value,
                              std::true_type, std::false_type>::type;

template <class T>
using is_unsigned_int =
    typename std::conditional<(is_integral<T>::value &&
                               std::is_unsigned<T>::value) ||
                                  is_unsigned_int128<T>::value,
                              std::true_type, std::false_type>::type;

template <class T>
using to_unsigned = typename std::conditional<
    is_signed_int128<T>::value, make_unsigned_int128<T>,
    typename std::conditional<std::is_signed<T>::value, std::make_unsigned<T>,
                              std::common_type<T>>::type>::type;

#else

template <class T> using is_integral = typename std::is_integral<T>;

template <class T>
using is_signed_int =
    typename std::conditional<is_integral<T>::value && std::is_signed<T>::value,
                              std::true_type, std::false_type>::type;

template <class T>
using is_unsigned_int =
    typename std::conditional<is_integral<T>::value &&
                                  std::is_unsigned<T>::value,
                              std::true_type, std::false_type>::type;

template <class T>
using to_unsigned =
    typename std::conditional<is_signed_int<T>::value, std::make_unsigned<T>,
                              std::common_type<T>>::type;

#endif

template <class T>
using is_signed_int_t = std::enable_if_t<is_signed_int<T>::value>;

template <class T>
using is_unsigned_int_t = std::enable_if_t<is_unsigned_int<T>::value>;

template <class T> using to_unsigned_t = typename to_unsigned<T>::type;

} // namespace internal

} // namespace atcoder

#endif // ATCODER_INTERNAL_TYPE_TRAITS_HPP

#ifndef ATCODER_FENWICKTREE_HPP
#define ATCODER_FENWICKTREE_HPP 1

#include <cassert>
#include <vector>

namespace atcoder {

// Reference: https://en.wikipedia.org/wiki/Fenwick_tree
template <class T> struct fenwick_tree {
  using U = internal::to_unsigned_t<T>;

public:
  fenwick_tree() : _n(0) {}
  fenwick_tree(int n) : _n(n), data(n) {}

  void add(int p, T x) {
    assert(0 <= p && p < _n);
    p++;
    while (p <= _n) {
      data[p - 1] += U(x);
      p += p & -p;
    }
  }

  T sum(int l, int r) {
    assert(0 <= l && l <= r && r <= _n);
    return sum(r) - sum(l);
  }

private:
  int _n;
  std::vector<U> data;

  U sum(int r) {
    U s = 0;
    while (r > 0) {
      s += data[r - 1];
      r -= r & -r;
    }
    return s;
  }
};

} // namespace atcoder

#endif // ATCODER_FENWICKTREE_HPP

using namespace std;
using namespace atcoder;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)
using ll = long long;
const ll MOD = 1000000007;
// const ll MOD=998244353;
const long long INF = 1LL << 60;
const double pi = acos(-1.0);
int dx[9] = {1, 0, -1, 0, 1, 1, -1, -1, 0};
int dy[9] = {0, 1, 0, -1, 1, -1, -1, 1, 0};

template <class T> inline bool chmin(T &a, T b) {
  if (a > b) {
    a = b;
    return true;
  }
  return false;
}
template <class T> inline bool chmax(T &a, T b) {
  if (a < b) {
    a = b;
    return true;
  }
  return false;
}

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  // cout << fixed << setprecision(15);

  ll N, Q;
  cin >> N;
  string S;
  cin >> S;
  cin >> Q;

  vector<fenwick_tree<int>> fw_vec(26, fenwick_tree<int>(N));
  rep(i, N) {
    ll c = S[i] - 'a';
    fw_vec[c].add(i, 1);
  }
  rep(i, Q) {
    int t;
    cin >> t;
    if (t == 1) {
      ll j;
      char chnc;
      cin >> j >> chnc;
      j--;
      ll c = S[j] - 'a';
      S[j] = chnc;
      ll nc = chnc - 'a';
      fw_vec[c].add(j, -1);
      fw_vec[nc].add(j, 1);
    } else {
      ll l, r;
      cin >> l >> r;
      l--;
      r--;
      ll ans = 0;
      rep(j, 26) {
        if (fw_vec[j].sum(l, r + 1))
          ans++;
      }
      cout << ans << '\n';
    }
  }

  return 0;
}