Problem p03095 (C++)

Buggy submission (status: Time Limit Exceeded):
#include <algorithm>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <vector>
#define _USE_MATH_DEFINES
#include <cassert>
#include <cfloat>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
using namespace std;

#define EPS 1e-12
#define ull unsigned long long
#define ll long long
#define VI vector<ll>
#define PII pair<ll, ll>
#define VVI vector<vector<ll>>
#define REP(i, n) for (int i = 0, _n = (n); (i) < (int)_n; ++i)
#define RANGE(i, a, b) for (int i = (int)a, _b = (int)(b); (i) < _b; ++i)
#define FOR(i, c)                                                              \
  for (__typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define ALL(c) (c).begin(), (c).end()
#define ALLR(c) (c).rbegin(), (c).rend()
#define PB push_back
#define MP(a, b) make_pair(a, b)
#define POPCOUNT __builtin_popcount
#define POPCOUNTLL __builtin_popcountll
#define CLEAR(table, v) memset(table, v, sizeof(table));
#define PRINT1(table, D0)                                                      \
  REP(d0, D0) cout << table[d0] << " ";                                        \
  cout << "\n";
#define PRINT2(table, D0, D1)                                                  \
  REP(d0, D0) {                                                                \
    REP(d1, D1) cout << table[d0][d1] << " ";                                  \
    cout << "\n";                                                              \
  }
#define PRINT3(table, D0, D1, D2)                                              \
  REP(d0, D0) {                                                                \
    REP(d1, D1) {                                                              \
      REP(d2, D2) cout << table[d0][d1][d2] << " ";                            \
      cout << "\n";                                                            \
    }                                                                          \
    cout << "\n";                                                              \
  }
#define UNIFORM_DOUBLE(a, b)                                                   \
  (((b - a) * (double)rand() / RAND_MAX) + a)      // [a, b)
#define UNIFORM_LL(a, b) (ll) UNIFORM_DOUBLE(a, b) // [a, b)
#define IN(v, lo, hi) ((lo) <= (v) && (v) < (hi))
#define DD(v) cout << #v << ": " << v << endl
template <typename T0, typename T1>
std::ostream &operator<<(std::ostream &os, const map<T0, T1> &v) {
  for (typename map<T0, T1>::const_iterator p = v.begin(); p != v.end(); p++) {
    os << p->first << ": " << p->second << " ";
  }
  return os;
}
template <typename T0, typename T1>
std::ostream &operator<<(std::ostream &os, const pair<T0, T1> &v) {
  os << v.first << ": " << v.second << " ";
  return os;
}
template <typename T>
std::ostream &operator<<(std::ostream &os, const vector<T> &v) {
  for (int i = 0; i < (int)v.size(); i++) {
    os << v[i] << " ";
  }
  return os;
}
template <typename T>
std::ostream &operator<<(std::ostream &os, const vector<vector<T>> &v) {
  for (int i = 0; i < (int)v.size(); i++) {
    os << v[i] << endl;
  }
  return os;
}
template <typename T>
std::ostream &operator<<(std::ostream &os, const set<T> &v) {
  vector<T> tmp(v.begin(), v.end());
  os << tmp;
  return os;
}
template <typename T>
std::ostream &operator<<(std::ostream &os, const deque<T> &v) {
  vector<T> tmp(v.begin(), v.end());
  os << tmp;
  return os;
}

#define MOD 1000000007LL
#define INF (1LL << 60)

struct modll {
  static const ll MODVAL;
  ll val;
  modll() : val(0) {}
  modll(ll v) : val(v) { normalize(); }
  void normalize() { val = (val + MODVAL) % MODVAL; }
  modll operator+(ll v) { return modll(val + v); }
  modll &operator+=(ll v) {
    val += v;
    normalize();
    return *this;
  }
  modll operator-(ll v) { return modll(val - v); }
  modll &operator-=(ll v) {
    val -= v;
    normalize();
    return *this;
  }
  modll operator*(ll v) { return modll(val * v); }
  modll &operator*=(ll v) {
    val *= v;
    normalize();
    return *this;
  }
  modll operator^(ll e) {
    modll x(val);
    modll v(1);
    for (; e; x = x * x, e >>= 1)
      if (e & 1)
        v = v * x;
    return v;
  } // pow
  modll inv() {
    modll x(val);
    return x ^ (MODVAL - 2);
  } // MODVAL must be prime number when use this!
  static modll inv(ll v) { return modll(v).inv(); }
  operator ll() { return val; }
};
const ll modll::MODVAL = 1000000007;
std::ostream &operator<<(std::ostream &os, const modll &v) {
  os << v.val;
  return os;
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  ll N;
  string s;
  while (cin >> N >> s) {
    vector<modll> co(26, 0);
    REP(i, N) co[s[i] - 'a'] += 1;
    modll ans = 0;
    RANGE(bi, 1, 1 << 26) {
      modll lans = 1;
      REP(ci, 26) {
        if (bi >> ci & 1)
          lans *= co[ci];
      }
      ans += lans;
    }
    cout << ans << endl;
  }

  return 0;
}


Fixed submission:
#include <algorithm>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <vector>
#define _USE_MATH_DEFINES
#include <cassert>
#include <cfloat>
#include <climits>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <ctime>
using namespace std;

#define EPS 1e-12
#define ull unsigned long long
#define ll long long
#define VI vector<ll>
#define PII pair<ll, ll>
#define VVI vector<vector<ll>>
#define REP(i, n) for (int i = 0, _n = (n); (i) < (int)_n; ++i)
#define RANGE(i, a, b) for (int i = (int)a, _b = (int)(b); (i) < _b; ++i)
#define FOR(i, c)                                                              \
  for (__typeof((c).begin()) i = (c).begin(); i != (c).end(); ++i)
#define ALL(c) (c).begin(), (c).end()
#define ALLR(c) (c).rbegin(), (c).rend()
#define PB push_back
#define MP(a, b) make_pair(a, b)
#define POPCOUNT __builtin_popcount
#define POPCOUNTLL __builtin_popcountll
#define CLEAR(table, v) memset(table, v, sizeof(table));
#define PRINT1(table, D0)                                                      \
  REP(d0, D0) cout << table[d0] << " ";                                        \
  cout << "\n";
#define PRINT2(table, D0, D1)                                                  \
  REP(d0, D0) {                                                                \
    REP(d1, D1) cout << table[d0][d1] << " ";                                  \
    cout << "\n";                                                              \
  }
#define PRINT3(table, D0, D1, D2)                                              \
  REP(d0, D0) {                                                                \
    REP(d1, D1) {                                                              \
      REP(d2, D2) cout << table[d0][d1][d2] << " ";                            \
      cout << "\n";                                                            \
    }                                                                          \
    cout << "\n";                                                              \
  }
#define UNIFORM_DOUBLE(a, b)                                                   \
  (((b - a) * (double)rand() / RAND_MAX) + a)      // [a, b)
#define UNIFORM_LL(a, b) (ll) UNIFORM_DOUBLE(a, b) // [a, b)
#define IN(v, lo, hi) ((lo) <= (v) && (v) < (hi))
#define DD(v) cout << #v << ": " << v << endl
template <typename T0, typename T1>
std::ostream &operator<<(std::ostream &os, const map<T0, T1> &v) {
  for (typename map<T0, T1>::const_iterator p = v.begin(); p != v.end(); p++) {
    os << p->first << ": " << p->second << " ";
  }
  return os;
}
template <typename T0, typename T1>
std::ostream &operator<<(std::ostream &os, const pair<T0, T1> &v) {
  os << v.first << ": " << v.second << " ";
  return os;
}
template <typename T>
std::ostream &operator<<(std::ostream &os, const vector<T> &v) {
  for (int i = 0; i < (int)v.size(); i++) {
    os << v[i] << " ";
  }
  return os;
}
template <typename T>
std::ostream &operator<<(std::ostream &os, const vector<vector<T>> &v) {
  for (int i = 0; i < (int)v.size(); i++) {
    os << v[i] << endl;
  }
  return os;
}
template <typename T>
std::ostream &operator<<(std::ostream &os, const set<T> &v) {
  vector<T> tmp(v.begin(), v.end());
  os << tmp;
  return os;
}
template <typename T>
std::ostream &operator<<(std::ostream &os, const deque<T> &v) {
  vector<T> tmp(v.begin(), v.end());
  os << tmp;
  return os;
}

#define MOD 1000000007LL
#define INF (1LL << 60)

struct modll {
  static const ll MODVAL;
  ll val;
  modll() : val(0) {}
  modll(ll v) : val(v) { normalize(); }
  void normalize() { val = (val + MODVAL) % MODVAL; }
  modll operator+(ll v) { return modll(val + v); }
  modll &operator+=(ll v) {
    val += v;
    normalize();
    return *this;
  }
  modll operator-(ll v) { return modll(val - v); }
  modll &operator-=(ll v) {
    val -= v;
    normalize();
    return *this;
  }
  modll operator*(ll v) { return modll(val * v); }
  modll &operator*=(ll v) {
    val *= v;
    normalize();
    return *this;
  }
  modll operator^(ll e) {
    modll x(val);
    modll v(1);
    for (; e; x = x * x, e >>= 1)
      if (e & 1)
        v = v * x;
    return v;
  } // pow
  modll inv() {
    modll x(val);
    return x ^ (MODVAL - 2);
  } // MODVAL must be prime number when use this!
  static modll inv(ll v) { return modll(v).inv(); }
  operator ll() { return val; }
};
const ll modll::MODVAL = 1000000007;
std::ostream &operator<<(std::ostream &os, const modll &v) {
  os << v.val;
  return os;
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  ll N;
  string s;
  while (cin >> N >> s) {
    vector<modll> co(26, 0);
    REP(i, N) co[s[i] - 'a'] += 1;
    modll ans = 1;
    REP(i, 26) ans *= co[i] + 1LL;
    ans -= 1;
    cout << ans << endl;
  }

  return 0;
}