Problem p02763 (C++)

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

using namespace std;

typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<int, int> Pi;
typedef vector<ll> Vec;
typedef vector<int> Vi;
typedef vector<string> Vs;
typedef vector<P> VP;
typedef vector<vector<ll>> VV;
typedef vector<vector<int>> VVi;
typedef vector<vector<vector<ll>>> VVV;
typedef vector<vector<vector<vector<ll>>>> VVVV;

#define REP(i, a, b) for (ll i = (a); i < (b); i++)
#define PER(i, a, b) for (ll i = (a); i >= (b); i--)
#define rep(i, n) REP(i, 0, n)
#define per(i, n) PER(i, n, 0)
const ll INF = 1e18 + 18;
const ll MAX = 100005;
const ll MOD = 1000000007;
#define Yes(n) cout << ((n) ? "Yes" : "No") << endl;
#define YES(n) cout << ((n) ? "YES" : "NO") << endl;
#define ALL(v) v.begin(), v.end()
#define rALL(v) v.rbegin(), v.rend()
#define pb(x) push_back(x)
#define mp(a, b) make_pair(a, b)
#define Each(a, b) for (auto &a : b)
#define REPM(i, mp) for (auto i = mp.begin(); i != mp.end(); ++i)
#ifdef LOCAL
#define dbg(x_) cerr << #x_ << ":" << x_ << endl;
#define dbgmap(mp)                                                             \
  cerr << #mp << ":" << endl;                                                  \
  for (auto i = mp.begin(); i != mp.end(); ++i) {                              \
    cerr << i->first << ":" << i->second << endl;                              \
  }
#define dbgarr(n, m, arr)                                                      \
  rep(i, n) {                                                                  \
    rep(j, m) { cerr << arr[i][j] << " "; }                                    \
    cerr << endl;                                                              \
  }
#define dbgdp(n, arr)                                                          \
  rep(i, n) { cerr << arr[i] << " "; }                                         \
  cerr << endl;
#define dbgmint(n, arr)                                                        \
  rep(i, n) { cerr << arr[i].x << " "; }                                       \
  cerr << endl;
#define dbgarrmint(n, m, arr)                                                  \
  rep(i, n) {                                                                  \
    rep(j, m) { cerr << arr[i][j].x << " "; }                                  \
    cerr << endl;                                                              \
  }
#else
#define dbg(...) 42
#define dbgmap(...) 42
#define dbgarr(...) 42
#define dbgdp(...) 42
#define dbgmint(...) 42
#define dbgarrmint(...) 42
#endif
#define out(a) cout << a << endl
#define out2(a, b) cout << a << " " << b << endl
#define vout(v)                                                                \
  rep(i, v.size()) { cout << v[i] << " "; }                                    \
  cout << endl
#define Uniq(v) v.erase(unique(v.begin(), v.end()), v.end())
#define fi first
#define se second

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

template <typename T1, typename T2>
ostream &operator<<(ostream &s, const pair<T1, T2> &p) {
  return s << "(" << p.first << ", " << p.second << ")";
}

template <typename T> istream &operator>>(istream &i, vector<T> &v) {
  rep(j, v.size()) i >> v[j];
  return i;
}

// vector
template <typename T> ostream &operator<<(ostream &s, const vector<T> &v) {
  int len = v.size();
  for (int i = 0; i < len; ++i) {
    s << v[i];
    if (i < len - 1)
      s << "	";
  }
  return s;
}

// 2 dimentional vector
template <typename T>
ostream &operator<<(ostream &s, const vector<vector<T>> &vv) {
  int len = vv.size();
  for (int i = 0; i < len; ++i) {
    s << vv[i] << endl;
  }
  return s;
}

// mint
struct mint {
  ll x; // typedef long long ll;
  mint(ll x = 0) : x((x % MOD + MOD) % MOD) {}
  mint &operator+=(const mint a) {
    if ((x += a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator-=(const mint a) {
    if ((x += MOD - a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator*=(const mint a) {
    (x *= a.x) %= MOD;
    return *this;
  }
  mint operator+(const mint a) const {
    mint res(*this);
    return res += a;
  }
  mint operator-(const mint a) const {
    mint res(*this);
    return res -= a;
  }
  mint operator*(const mint a) const {
    mint res(*this);
    return res *= a;
  }
  mint pow(ll t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }

  // for prime MOD
  mint inv() const { return pow(MOD - 2); }
  mint &operator/=(const mint a) { return (*this) *= a.inv(); }
  mint operator/(const mint a) const {
    mint res(*this);
    return res /= a;
  }
};

struct combination {
  vector<mint> fact, ifact;
  combination(int n) : fact(n + 1), ifact(n + 1) {
    assert(n < MOD);
    fact[0] = 1;
    for (int i = 1; i <= n; ++i)
      fact[i] = fact[i - 1] * i;
    ifact[n] = fact[n].inv();
    for (int i = n; i >= 1; --i)
      ifact[i - 1] = ifact[i] * i;
  }
  mint operator()(int n, int k) {
    if (k < 0 || k > n)
      return 0;
    return fact[n] * ifact[k] * ifact[n - k];
  }
};

template <typename Monoid> struct SegmentTree {
  using F = function<Monoid(Monoid, Monoid)>;

  int sz;
  vector<Monoid> seg;

  const F f;
  const Monoid M1;

  SegmentTree(int n, const F f, const Monoid &M1) : f(f), M1(M1) {
    sz = 1;
    while (sz < n)
      sz <<= 1;
    seg.assign(2 * sz, M1);
  }

  void set(int k, const Monoid &x) { seg[k + sz] = x; }

  void build() {
    for (int k = sz - 1; k > 0; k--) {
      seg[k] = f(seg[2 * k + 0], seg[2 * k + 1]);
    }
  }

  void update(int k, const Monoid &x) {
    k += sz;
    seg[k] = x;
    while (k >>= 1) {
      seg[k] = f(seg[2 * k + 0], seg[2 * k + 1]);
    }
  }

  Monoid query(int a, int b) {
    Monoid L = M1, R = M1;
    for (a += sz, b += sz; a < b; a >>= 1, b >>= 1) {
      if (a & 1)
        L = f(L, seg[a++]);
      if (b & 1)
        R = f(seg[--b], R);
    }
    return f(L, R);
  }

  Monoid operator[](const int &k) const { return seg[k + sz]; }

  template <typename C>
  int find_subtree(int a, const C &check, Monoid &M, bool type) {
    while (a < sz) {
      Monoid nxt = type ? f(seg[2 * a + type], M) : f(M, seg[2 * a + type]);
      if (check(nxt))
        a = 2 * a + type;
      else
        M = nxt, a = 2 * a + 1 - type;
    }
    return a - sz;
  }

  template <typename C> int find_first(int a, const C &check) {
    Monoid L = M1;
    if (a <= 0) {
      if (check(f(L, seg[1])))
        return find_subtree(1, check, L, false);
      return -1;
    }
    int b = sz;
    for (a += sz, b += sz; a < b; a >>= 1, b >>= 1) {
      if (a & 1) {
        Monoid nxt = f(L, seg[a]);
        if (check(nxt))
          return find_subtree(a, check, L, false);
        L = nxt;
        ++a;
      }
    }
    return -1;
  }

  template <typename C> int find_last(int b, const C &check) {
    Monoid R = M1;
    if (b >= sz) {
      if (check(f(seg[1], R)))
        return find_subtree(1, check, R, true);
      return -1;
    }
    int a = sz;
    for (b += sz; a < b; a >>= 1, b >>= 1) {
      if (b & 1) {
        Monoid nxt = f(seg[--b], R);
        if (check(nxt))
          return find_subtree(b, check, R, true);
        R = nxt;
      }
    }
    return -1;
  }
};

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << std::setprecision(10);

  ll n;
  string str;
  cin >> n >> str;
  ll Q;
  cin >> Q;
  auto f = [](ll a, ll b) { return a + b; };
  vector<SegmentTree<ll>> vecseg(26, SegmentTree<ll>(n, f, 0));
  rep(i, n) {
    vecseg[i].build();
    vecseg[str[i] - 'a'].update(i, 1);
  }
  while (Q--) {
    ll q;
    cin >> q;
    if (q == 1) {
      ll x;
      char c;
      cin >> x >> c;
      x--;
      char cur = str[x];
      vecseg[cur - 'a'].update(x, vecseg[cur - 'a'].query(x, x + 1) - 1);
      vecseg[c - 'a'].update(x, vecseg[cur - 'a'].query(x, x + 1) + 1);
      str[x] = c;
    } else {
      ll l, r;
      cin >> l >> r;
      l--;
      r--;
      ll ans = 0;
      rep(i, 26) {
        ll cnt = vecseg[i].query(l, r + 1);
        if (cnt > 0) {
          dbg(i);
          ans++;
        }
      }
      out(ans);
    }
  }
  //    dbg(del);
  //    dbg(add);
  return 0;
}


Fixed submission:
#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
typedef pair<ll, ll> P;
typedef pair<int, int> Pi;
typedef vector<ll> Vec;
typedef vector<int> Vi;
typedef vector<string> Vs;
typedef vector<P> VP;
typedef vector<vector<ll>> VV;
typedef vector<vector<int>> VVi;
typedef vector<vector<vector<ll>>> VVV;
typedef vector<vector<vector<vector<ll>>>> VVVV;

#define REP(i, a, b) for (ll i = (a); i < (b); i++)
#define PER(i, a, b) for (ll i = (a); i >= (b); i--)
#define rep(i, n) REP(i, 0, n)
#define per(i, n) PER(i, n, 0)
const ll INF = 1e18 + 18;
const ll MAX = 100005;
const ll MOD = 1000000007;
#define Yes(n) cout << ((n) ? "Yes" : "No") << endl;
#define YES(n) cout << ((n) ? "YES" : "NO") << endl;
#define ALL(v) v.begin(), v.end()
#define rALL(v) v.rbegin(), v.rend()
#define pb(x) push_back(x)
#define mp(a, b) make_pair(a, b)
#define Each(a, b) for (auto &a : b)
#define REPM(i, mp) for (auto i = mp.begin(); i != mp.end(); ++i)
#ifdef LOCAL
#define dbg(x_) cerr << #x_ << ":" << x_ << endl;
#define dbgmap(mp)                                                             \
  cerr << #mp << ":" << endl;                                                  \
  for (auto i = mp.begin(); i != mp.end(); ++i) {                              \
    cerr << i->first << ":" << i->second << endl;                              \
  }
#define dbgarr(n, m, arr)                                                      \
  rep(i, n) {                                                                  \
    rep(j, m) { cerr << arr[i][j] << " "; }                                    \
    cerr << endl;                                                              \
  }
#define dbgdp(n, arr)                                                          \
  rep(i, n) { cerr << arr[i] << " "; }                                         \
  cerr << endl;
#define dbgmint(n, arr)                                                        \
  rep(i, n) { cerr << arr[i].x << " "; }                                       \
  cerr << endl;
#define dbgarrmint(n, m, arr)                                                  \
  rep(i, n) {                                                                  \
    rep(j, m) { cerr << arr[i][j].x << " "; }                                  \
    cerr << endl;                                                              \
  }
#else
#define dbg(...) 42
#define dbgmap(...) 42
#define dbgarr(...) 42
#define dbgdp(...) 42
#define dbgmint(...) 42
#define dbgarrmint(...) 42
#endif
#define out(a) cout << a << endl
#define out2(a, b) cout << a << " " << b << endl
#define vout(v)                                                                \
  rep(i, v.size()) { cout << v[i] << " "; }                                    \
  cout << endl
#define Uniq(v) v.erase(unique(v.begin(), v.end()), v.end())
#define fi first
#define se second

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

template <typename T1, typename T2>
ostream &operator<<(ostream &s, const pair<T1, T2> &p) {
  return s << "(" << p.first << ", " << p.second << ")";
}

template <typename T> istream &operator>>(istream &i, vector<T> &v) {
  rep(j, v.size()) i >> v[j];
  return i;
}

// vector
template <typename T> ostream &operator<<(ostream &s, const vector<T> &v) {
  int len = v.size();
  for (int i = 0; i < len; ++i) {
    s << v[i];
    if (i < len - 1)
      s << "	";
  }
  return s;
}

// 2 dimentional vector
template <typename T>
ostream &operator<<(ostream &s, const vector<vector<T>> &vv) {
  int len = vv.size();
  for (int i = 0; i < len; ++i) {
    s << vv[i] << endl;
  }
  return s;
}

// mint
struct mint {
  ll x; // typedef long long ll;
  mint(ll x = 0) : x((x % MOD + MOD) % MOD) {}
  mint &operator+=(const mint a) {
    if ((x += a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator-=(const mint a) {
    if ((x += MOD - a.x) >= MOD)
      x -= MOD;
    return *this;
  }
  mint &operator*=(const mint a) {
    (x *= a.x) %= MOD;
    return *this;
  }
  mint operator+(const mint a) const {
    mint res(*this);
    return res += a;
  }
  mint operator-(const mint a) const {
    mint res(*this);
    return res -= a;
  }
  mint operator*(const mint a) const {
    mint res(*this);
    return res *= a;
  }
  mint pow(ll t) const {
    if (!t)
      return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1)
      a *= *this;
    return a;
  }

  // for prime MOD
  mint inv() const { return pow(MOD - 2); }
  mint &operator/=(const mint a) { return (*this) *= a.inv(); }
  mint operator/(const mint a) const {
    mint res(*this);
    return res /= a;
  }
};

struct combination {
  vector<mint> fact, ifact;
  combination(int n) : fact(n + 1), ifact(n + 1) {
    assert(n < MOD);
    fact[0] = 1;
    for (int i = 1; i <= n; ++i)
      fact[i] = fact[i - 1] * i;
    ifact[n] = fact[n].inv();
    for (int i = n; i >= 1; --i)
      ifact[i - 1] = ifact[i] * i;
  }
  mint operator()(int n, int k) {
    if (k < 0 || k > n)
      return 0;
    return fact[n] * ifact[k] * ifact[n - k];
  }
};

template <typename Monoid> struct SegmentTree {
  using F = function<Monoid(Monoid, Monoid)>;

  int sz;
  vector<Monoid> seg;

  const F f;
  const Monoid M1;

  SegmentTree(int n, const F f, const Monoid &M1) : f(f), M1(M1) {
    sz = 1;
    while (sz < n)
      sz <<= 1;
    seg.assign(2 * sz, M1);
  }

  void set(int k, const Monoid &x) { seg[k + sz] = x; }

  void build() {
    for (int k = sz - 1; k > 0; k--) {
      seg[k] = f(seg[2 * k + 0], seg[2 * k + 1]);
    }
  }

  void update(int k, const Monoid &x) {
    k += sz;
    seg[k] = x;
    while (k >>= 1) {
      seg[k] = f(seg[2 * k + 0], seg[2 * k + 1]);
    }
  }

  Monoid query(int a, int b) {
    Monoid L = M1, R = M1;
    for (a += sz, b += sz; a < b; a >>= 1, b >>= 1) {
      if (a & 1)
        L = f(L, seg[a++]);
      if (b & 1)
        R = f(seg[--b], R);
    }
    return f(L, R);
  }

  Monoid operator[](const int &k) const { return seg[k + sz]; }

  template <typename C>
  int find_subtree(int a, const C &check, Monoid &M, bool type) {
    while (a < sz) {
      Monoid nxt = type ? f(seg[2 * a + type], M) : f(M, seg[2 * a + type]);
      if (check(nxt))
        a = 2 * a + type;
      else
        M = nxt, a = 2 * a + 1 - type;
    }
    return a - sz;
  }

  template <typename C> int find_first(int a, const C &check) {
    Monoid L = M1;
    if (a <= 0) {
      if (check(f(L, seg[1])))
        return find_subtree(1, check, L, false);
      return -1;
    }
    int b = sz;
    for (a += sz, b += sz; a < b; a >>= 1, b >>= 1) {
      if (a & 1) {
        Monoid nxt = f(L, seg[a]);
        if (check(nxt))
          return find_subtree(a, check, L, false);
        L = nxt;
        ++a;
      }
    }
    return -1;
  }

  template <typename C> int find_last(int b, const C &check) {
    Monoid R = M1;
    if (b >= sz) {
      if (check(f(seg[1], R)))
        return find_subtree(1, check, R, true);
      return -1;
    }
    int a = sz;
    for (b += sz; a < b; a >>= 1, b >>= 1) {
      if (b & 1) {
        Monoid nxt = f(seg[--b], R);
        if (check(nxt))
          return find_subtree(b, check, R, true);
        R = nxt;
      }
    }
    return -1;
  }
};

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  cout << std::setprecision(10);

  ll n;
  string str;
  cin >> n >> str;
  ll Q;
  cin >> Q;
  auto f = [](ll a, ll b) { return a + b; };
  vector<SegmentTree<ll>> vecseg(26, SegmentTree<ll>(n, f, 0));
  rep(i, 26) { vecseg[i].build(); }
  rep(i, n) { vecseg[str[i] - 'a'].update(i, 1); }
  while (Q--) {
    ll q;
    cin >> q;
    if (q == 1) {
      ll x;
      char c;
      cin >> x >> c;
      x--;
      char cur = str[x];
      vecseg[cur - 'a'].update(x, vecseg[cur - 'a'].query(x, x + 1) - 1);
      vecseg[c - 'a'].update(x, vecseg[cur - 'a'].query(x, x + 1) + 1);
      str[x] = c;
    } else {
      ll l, r;
      cin >> l >> r;
      l--;
      r--;
      ll ans = 0;
      rep(i, 26) {
        ll cnt = vecseg[i].query(l, r + 1);
        if (cnt > 0) {
          dbg(i);
          ans++;
        }
      }
      out(ans);
    }
  }
  //    dbg(del);
  //    dbg(add);
  return 0;
}