Problem p02632 (C++) — buggy submission, verdict: Runtime Error

#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")
#pragma GCC optimize("unroll-loops")
// #pragma warning(disable : 4996)

#ifdef _MSC_VER
#include <intrin.h>
#define __builtin_popcount __popcnt
#define __builtin_popcountll __popcnt64
#endif

#include <limits.h>
#include <math.h>
#include <time.h>

#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <complex>
#include <cstdio>
#include <cstring>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>

using namespace std;

#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 FORR(i, m, n) for (int i = m - 1; i >= n; --i)
#define SORT(v, n) sort(v, v + n);
#define VSORT(v) sort(v.begin(), v.end());
#define REVERSE(v, n) reverse(v, v + n);
#define VREVERSE(v) reverse(v.begin(), v.end())
#define ll long long
#define print(x) cout << (x) << '\\n'
#define pe(x) cout << (x) << " "
#define DEBUG(x) cout << #x << ": " << x << endl
#define lb(v, n) lower_bound(v.begin(), v.end(), (n))
#define ub(v, n) upper_bound(v.begin(), v.end(), (n))
#define int long long
#define double long double
#define all(x) (x).begin(), (x).end()
#define print_space(v)                                                         \\
  REP(i, v.size()) cout << v[i] << ((i == v.size() - 1) ? "\\n" : " ")
template <typename T1, typename T2> inline void chmin(T1 &a, T2 b) {
  if (a > b)
    a = b;
}
template <typename T1, typename T2> inline void chmax(T1 &a, T2 b) {
  if (a < b)
    a = b;
}
void fail() {
  cout << -1 << endl;
  exit(0);
}

typedef pair<int, int> pii;
typedef pair<long long, long long> pll;
std::random_device rd;
std::mt19937 mt(rd());
constexpr ll MOD = 1e9 + 7;
constexpr int MAX = 2220020;
const double pi = acos(-1);
constexpr double EPS = 1e-8;
constexpr ll LINF = 1e18 + 1;
constexpr int INF = 1e9 + 1;
// const int dx[4] = { 0,0,-1,1 }, dy[4] = { 1,-1,0,0 };

long long fac[MAX], finv[MAX], inv[MAX];

// テーブルを作る前処理
void COMinit() {
  fac[0] = fac[1] = 1;
  finv[0] = finv[1] = 1;
  inv[1] = 1;
  for (int i = 2; i < MAX; i++) {
    fac[i] = fac[i - 1] * i % MOD;
    inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
    finv[i] = finv[i - 1] * inv[i] % MOD;
  }
}

// 二項係数計算
long long COM(int n, int k) {
  if (n < k)
    return 0;
  if (n < 0 || k < 0)
    return 0;
  return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}
ll add(ll x, ll y) {
  x += y;
  if (x >= MOD)
    return x - MOD;
  return x;
}
ll sub(ll x, ll y) {
  x -= y;
  if (x < 0)
    return x + MOD;
  return x;
}
ll mult(ll x, ll y) { return (x * y) % MOD; }
ll bin_pow(ll x, ll p) {
  if (p == 0)
    return 1;
  if (p & 1)
    return mult(x, bin_pow(x, p - 1));
  return bin_pow(mult(x, x), p / 2);
}

ll mo = 1000000007;

ll modpow(ll a, ll n) {
  ll r = 1;
  while (n)
    r = r * ((n % 2) ? a : 1) % mo, a = a * a % mo, n >>= 1;
  return r;
}

// ll combi(ll N_, ll C_) {
//	const int NUM_ = 400001;
//	static ll fact[NUM_ + 1], factr[NUM_ + 1], inv[NUM_ + 1];
//	if (fact[0] == 0) {
//		inv[1] = fact[0] = factr[0] = 1;
//		for (int i = 2; i <= NUM_; ++i) inv[i] = inv[mo % i] * (mo - mo /
//i) % mo; 		for (int i = 1; i <= NUM_; ++i) fact[i] = fact[i - 1] * i%mo,
//factr[i] = factr[i - 1] * inv[i] % mo;
//	}
//	if (C_<0 || C_>N_) return 0;
//	return factr[C_] * fact[N_] % mo*factr[N_ - C_] % mo;
//}
ll hcomb(int P_, int Q_) {
  return (P_ == 0 && Q_ == 0) ? 1 : COM(P_ + Q_ - 1, Q_);
}

int M, L;
string S;
ll p[2][2210101];
int r25_26;

vector<int> V[2201010];

void create(int len) {
  if (V[len].size())
    return;
  // int i;
  int a = 1;
  ll sum = 0;
  REP(i, 1000002) {
    sum += mult(hcomb(len, i), a);
    if (sum >= mo)
      sum -= mo;
    V[len].push_back(sum);
    a = mult(a, r25_26);
  }
}

void solve() {
  // print("a");
  COMinit();
  int N = 1000000;
  cin >> N; // cin >> N;
            // REP(_, 1000000) S += 'a';  // cin >> S;
  cin >> S;
  // int M = S.size();

  p[0][0] = p[1][0] = 1;
  REP(i, 1000002)
  p[0][i + 1] = p[0][i] * 25 % mo,
           p[1][i + 1] = p[1][i] * 26 % mo;
  r25_26 = 25 * modpow(26, mo - 2) % mo;

  L = S.size();
  create(L);
  N += L;
  cout << V[L][N - L] * p[1][N - L] % mo << endl;
  // mint ans = (mint)COM(N + M, M)*((mint)26).pow(N);
  // print(ans);
}

signed main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  // mt.seed((int)(time(0)));
  // int q;
  // cin >> q;
  // while (q--)
  solve();
}


Error: -11

Fixed submission:

#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")
#pragma GCC optimize("unroll-loops")
// #pragma warning(disable : 4996)

#ifdef _MSC_VER
#include <intrin.h>
#define __builtin_popcount __popcnt
#define __builtin_popcountll __popcnt64
#endif

#include <limits.h>
#include <math.h>
#include <time.h>

#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <complex>
#include <cstdio>
#include <cstring>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <map>
#include <numeric>
#include <queue>
#include <random>
#include <set>
#include <stack>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <vector>

using namespace std;

#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 FORR(i, m, n) for (int i = m - 1; i >= n; --i)
#define SORT(v, n) sort(v, v + n);
#define VSORT(v) sort(v.begin(), v.end());
#define REVERSE(v, n) reverse(v, v + n);
#define VREVERSE(v) reverse(v.begin(), v.end())
#define ll long long
#define print(x) cout << (x) << '\\n'
#define pe(x) cout << (x) << " "
#define DEBUG(x) cout << #x << ": " << x << endl
#define lb(v, n) lower_bound(v.begin(), v.end(), (n))
#define ub(v, n) upper_bound(v.begin(), v.end(), (n))
#define int long long
#define double long double
#define all(x) (x).begin(), (x).end()
#define print_space(v)                                                         \\
  REP(i, v.size()) cout << v[i] << ((i == v.size() - 1) ? "\\n" : " ")
template <typename T1, typename T2> inline void chmin(T1 &a, T2 b) {
  if (a > b)
    a = b;
}
template <typename T1, typename T2> inline void chmax(T1 &a, T2 b) {
  if (a < b)
    a = b;
}
void fail() {
  cout << -1 << endl;
  exit(0);
}

typedef pair<int, int> pii;
typedef pair<long long, long long> pll;
std::random_device rd;
std::mt19937 mt(rd());
constexpr ll MOD = 1e9 + 7;
constexpr int MAX = 2220020;
const double pi = acos(-1);
constexpr double EPS = 1e-8;
constexpr ll LINF = 1e18 + 1;
constexpr int INF = 1e9 + 1;
// const int dx[4] = { 0,0,-1,1 }, dy[4] = { 1,-1,0,0 };

long long fac[MAX], finv[MAX], inv[MAX];

// テーブルを作る前処理
void COMinit() {
  fac[0] = fac[1] = 1;
  finv[0] = finv[1] = 1;
  inv[1] = 1;
  for (int i = 2; i < MAX; i++) {
    fac[i] = fac[i - 1] * i % MOD;
    inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
    finv[i] = finv[i - 1] * inv[i] % MOD;
  }
}

// 二項係数計算
long long COM(int n, int k) {
  if (n < k)
    return 0;
  if (n < 0 || k < 0)
    return 0;
  return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}
ll add(ll x, ll y) {
  x += y;
  if (x >= MOD)
    return x - MOD;
  return x;
}
ll sub(ll x, ll y) {
  x -= y;
  if (x < 0)
    return x + MOD;
  return x;
}
ll mult(ll x, ll y) { return (x * y) % MOD; }
ll bin_pow(ll x, ll p) {
  if (p == 0)
    return 1;
  if (p & 1)
    return mult(x, bin_pow(x, p - 1));
  return bin_pow(mult(x, x), p / 2);
}

const int mod = 1000000007;
// const int mod = 998244353;
struct mint {
  ll x; // typedef long long ll;
  mint(ll x = 0) : x((x % mod + mod) % mod) {}
  mint operator-() const { return mint(-x); }
  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 { return mint(*this) += a; }
  mint operator-(const mint a) const { return mint(*this) -= a; }
  mint operator*(const mint a) const { return mint(*this) *= 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 { return mint(*this) /= a; }
};
istream &operator>>(istream &is, const mint &a) { return is >> a.x; }
ostream &operator<<(ostream &os, const mint &a) { return os << a.x; }

ll mo = 1000000007;

ll modpow(ll a, ll n) {
  ll r = 1;
  while (n)
    r = r * ((n % 2) ? a : 1) % mo, a = a * a % mo, n >>= 1;
  return r;
}

// ll combi(ll N_, ll C_) {
//	const int NUM_ = 400001;
//	static ll fact[NUM_ + 1], factr[NUM_ + 1], inv[NUM_ + 1];
//	if (fact[0] == 0) {
//		inv[1] = fact[0] = factr[0] = 1;
//		for (int i = 2; i <= NUM_; ++i) inv[i] = inv[mo % i] * (mo - mo /
//i) % mo; 		for (int i = 1; i <= NUM_; ++i) fact[i] = fact[i - 1] * i%mo,
//factr[i] = factr[i - 1] * inv[i] % mo;
//	}
//	if (C_<0 || C_>N_) return 0;
//	return factr[C_] * fact[N_] % mo*factr[N_ - C_] % mo;
// }
ll hcomb(int P_, int Q_) {
  return (P_ == 0 && Q_ == 0) ? 1 : COM(P_ + Q_ - 1, Q_);
}

int M, L;
string S;
ll p[2][2210101];
int r25_26;

vector<int> V[2201010];

void create(int len) {
  if (V[len].size())
    return;
  int i;
  int a = 1;
  ll sum = 0;
  REP(i, 2000002) {
    sum += mult(hcomb(len, i), a);
    if (sum >= mo)
      sum -= mo;
    V[len].push_back(sum);
    a = mult(a, r25_26);
  }
}

void solve() {
  COMinit();
  int N;
  cin >> N;
  string S;
  cin >> S;
  int M = S.size();

  p[0][0] = p[1][0] = 1;
  REP(i, 2000002)
  p[0][i + 1] = p[0][i] * 25 % mo,
           p[1][i + 1] = p[1][i] * 26 % mo;
  r25_26 = 25 * modpow(26, mo - 2) % mo;

  L = S.size();
  create(L);
  N += L;
  cout << V[L][N - L] * p[1][N - L] % mo << endl;
  // mint ans = (mint)COM(N + M, M)*((mint)26).pow(N);
  // print(ans);
}

signed main() {
  cin.tie(0);
  ios::sync_with_stdio(false);
  // mt.seed((int)(time(0)));
  // int q;
  // cin >> q;
  // while (q--)
  solve();
}