Problem p02734 (C++)

Buggy submission (status: Time Limit Exceeded):
#ifdef LOCAL
#pragma GCC optimize("O0")
#else
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx")
#endif

#include <algorithm>
#include <bitset>
#include <cmath>
#include <functional>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <tuple>
#include <utility>
#include <vector>

using namespace std;

using ll = long long;
using VI = vector<int>;
using VVI = vector<vector<int>>;
using VLL = vector<ll>;
using VVLL = vector<vector<ll>>;
using VB = vector<bool>;
using VVB = vector<vector<bool>>;
using PII = pair<int, int>;
template <typename T> using minheap = priority_queue<T, vector<T>, greater<T>>;
const int INF = 1e9 + 7;
const ll INF_LL = (ll)1e18 + 7;

#define __overload3(_1, _2, _3, name, ...) name
#define rep(...)                                                               \
  __overload3(__VA_ARGS__, repFromUntil, repUntil, repeat)(__VA_ARGS__)
#define repeat(times) repFromUntil(__name, 0, times)
#define repUntil(name, times) repFromUntil(name, 0, times)
#define repFromUntil(name, from, until)                                        \
  for (int name = from, name##__until = (until); name < name##__until; name++)
#define repr(...)                                                              \
  __overload3(__VA_ARGS__, reprFromUntil, reprUntil, repeat)(__VA_ARGS__)
#define reprUntil(name, times) reprFromUntil(name, 0, times)
#define reprFromUntil(name, from, until)                                       \
  for (int name = until - 1, name##__from = (from); name >= name##__from;      \
       name--)

#define EXIT(out)                                                              \
  do {                                                                         \
    OUT(out);                                                                  \
    exit(0);                                                                   \
  } while (0)

#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define _1 first
#define _2 second

#define debug(v)                                                               \
  do {                                                                         \
    debugos << "L" << __LINE__ << " " << #v << " > ";                          \
    debugos << (v) << newl;                                                    \
  } while (0)
#define debugv(v)                                                              \
  do {                                                                         \
    debugos << "L" << __LINE__ << " " << #v << " > ";                          \
    for (auto e : (v)) {                                                       \
      debugos << e << " ";                                                     \
    }                                                                          \
    debugos << newl;                                                           \
  } while (0)
#define debuga(m, w)                                                           \
  do {                                                                         \
    debugos << "L" << __LINE__ << " " << #m << " > ";                          \
    for (int x = 0; x < (w); x++) {                                            \
      debugos << (m)[x] << " ";                                                \
    }                                                                          \
    debugos << newl;                                                           \
  } while (0)
#define debugaa(m, h, w)                                                       \
  do {                                                                         \
    debugos << "L" << __LINE__ << " " << #m << " > \n";                        \
    for (int y = 0; y < (h); y++) {                                            \
      for (int x = 0; x < (w); x++) {                                          \
        debugos << (m)[y][x] << " ";                                           \
      }                                                                        \
      debugos << newl;                                                         \
    }                                                                          \
  } while (0)

#define newl "\n"
constexpr int dr[] = {1, -1, 0, 0};
constexpr int dc[] = {0, 0, 1, -1};

bool inside(int r, int c, int H, int W) {
  return 0 <= r and r < H and 0 <= c and c < W;
}

template <typename T> bool chmin(T &var, T x) {
  if (var > x) {
    var = x;
    return true;
  } else
    return false;
}

template <typename T> bool chmax(T &var, T x) {
  if (var < x) {
    var = x;
    return true;
  } else
    return false;
}

template <typename T> struct minT {
  T operator()(T a, T b) { return min(a, b); }
};

template <typename T> struct maxT {
  T operator()(T a, T b) { return max(a, b); }
};

template <typename T> int sgn(T val) { return (T(0) < val) - (val < T(0)); }

ll power(ll e, int t, ll mod = INF_LL) {
  ll res = 1;
  while (t) {
    if (t & 1)
      res = (res * e) % mod;
    t >>= 1;
    e = (e * e) % mod;
  }
  return res;
}

template <typename T> T divceil(T, T);

template <typename T> T divfloor(T m, T d) {
  if (sgn(m) * sgn(d) >= 0)
    return m / d;
  else
    return -divceil(abs(m), abs(d));
}

template <typename T> T divceil(T m, T d) {
  if (m >= 0 and d > 0)
    return (m + d - 1) / d;
  else if (m < 0 and d < 0)
    return divceil(-m, -d);
  else
    return -divfloor(abs(m), abs(d));
}

template <typename T> vector<T> make_v(size_t a, T b) {
  return vector<T>(a, b);
}

template <typename... Ts> auto make_v(size_t a, Ts... ts) {
  return vector<decltype(make_v(ts...))>(a, make_v(ts...));
}

string operator*(const string &s, int times) {
  string res = "";
  rep(times) res += s;
  return res;
}

class MyScanner {
public:
  int offset = 0;
  template <typename T> void input_integer(T &var) {
    var = 0;
    T sign = 1;
    int cc = getchar();
    for (; cc < '0' || '9' < cc; cc = getchar())
      if (cc == '-')
        sign = -1;
    for (; '0' <= cc && cc <= '9'; cc = getchar())
      var = (var << 3) + (var << 1) + cc - '0';
    var = var * sign;
    var += offset;
  }
  int c() {
    char c;
    while (c = getchar(), c == ' ' or c == '\n')
      ;
    return c;
  }
  MyScanner &operator>>(char &var) {
    var = c();
    return *this;
  }
  MyScanner &operator>>(int &var) {
    input_integer<int>(var);
    return *this;
  }
  MyScanner &operator>>(ll &var) {
    input_integer<ll>(var);
    return *this;
  }
  MyScanner &operator>>(string &var) {
    int cc = getchar();
    for (; !isvisiblechar(cc); cc = getchar())
      ;
    for (; isvisiblechar(cc); cc = getchar())
      var.push_back(cc);
    return *this;
  }
  template <typename T> operator T() {
    T x;
    *this >> x;
    return x;
  }
  template <typename T> void operator()(T &t) { *this >> t; }
  template <typename T, typename... Ts> void operator()(T &t, Ts &...ts) {
    *this >> t;
    this->operator()(ts...);
  }
  template <typename Iter> void iter(Iter first, Iter last) {
    while (first != last)
      *this >> *first, first++;
  }
  VI vi(int n) {
    VI res(n);
    iter(all(res));
    return res;
  }
  VVI vvi(int n, int m) {
    VVI res(n);
    rep(i, n) res[i] = vi(m);
    return res;
  }
  VLL vll(int n) {
    VLL res(n);
    iter(all(res));
    return res;
  }
  VVLL vvll(int n, int m) {
    VVLL res(n);
    rep(i, n) res[i] = vll(m);
    return res;
  }
  template <typename T> vector<T> v(int n) {
    vector<T> res(n);
    iter(all(res));
    return res;
  }

private:
  int isvisiblechar(int c) { return 0x21 <= c && c <= 0x7E; }
} IN, IN1{-1};

class MyPrinter {
public:
  template <typename T> void output_integer(T var) {
    if (var == 0) {
      putchar('0');
      return;
    }
    if (var < 0)
      putchar('-'), var = -var;
    char stack[32];
    int stack_p = 0;
    while (var)
      stack[stack_p++] = '0' + (var % 10), var /= 10;
    while (stack_p)
      putchar(stack[--stack_p]);
  }
  MyPrinter &operator<<(char c) {
    putchar(c);
    return *this;
  }
  template <typename T> MyPrinter &operator<<(T var) {
    output_integer<T>(var);
    return *this;
  }
  MyPrinter &operator<<(char *str_p) {
    while (*str_p)
      putchar(*(str_p++));
    return *this;
  }
  MyPrinter &operator<<(const char *str_p) {
    while (*str_p)
      putchar(*(str_p++));
    return *this;
  }
  MyPrinter &operator<<(const string &str) {
    const char *p = str.c_str();
    const char *l = p + str.size();
    while (p < l)
      putchar(*p++);
    return *this;
  }
  // MyPrinter& operator<<(const modint& var) { output_integer<ll>(var.value);
  // return *this; }
  template <typename T> void operator()(T x) { *this << x << newl; }
  template <typename T, typename... Ts> void operator()(T x, Ts... xs) {
    *this << x << " ";
    this->operator()(xs...);
  }
  template <typename Iter> void iter(Iter s, Iter t) {
    if (s == t)
      *this << "\n";
    else {
      for (; s != t; s++) {
        *this << *s << " \n"[next(s, 1) == t];
      }
    }
  }
  template <typename Range> void range(const Range &r) {
    iter(begin(r), end(r));
  }
} OUT;

class DebugPrint {
public:
  template <typename T> DebugPrint &operator<<(const T &v) {
#ifdef LOCAL
    cerr << v;
#endif
    return *this;
  }
} debugos;
class modint;
constexpr modint pow(modint, size_t);
constexpr ll MOD = 998244353;

class modint {
public:
  ll value;

  constexpr modint(const ll x = 0) noexcept : value(x) {
    value %= MOD;
    if (value < 0)
      value += MOD;
  }
  constexpr bool operator==(const modint &rhs) { return value == rhs.value; }
  constexpr bool operator!=(const modint &rhs) { return value != rhs.value; }
  constexpr modint operator+(const modint &rhs) const {
    return modint(*this) += rhs;
  }
  constexpr modint operator-(const modint &rhs) const {
    return modint(*this) -= rhs;
  }
  constexpr modint operator*(const modint &rhs) const {
    return modint(*this) *= rhs;
  }
  constexpr modint operator/(const modint &rhs) const {
    return modint(*this) /= rhs;
  }
  constexpr modint &operator+=(const modint &rhs) {
    value += rhs.value;
    if (value >= MOD)
      value -= MOD;
    return *this;
  }
  constexpr modint &operator-=(const modint &rhs) {
    if (value < rhs.value)
      value += MOD;
    value -= rhs.value;
    return *this;
  }
  constexpr modint &operator*=(const modint &rhs) {
    value = value * rhs.value % MOD;
    return *this;
  }
  constexpr modint &operator/=(const modint &rhs) {
    return *this *= pow(rhs, MOD - 2);
  }
  constexpr modint &operator++() { return *this += 1; }
  constexpr modint operator++(int) {
    modint tmp(*this);
    ++(*this);
    return tmp;
  }
  constexpr modint &operator--() { return *this -= 1; }
  constexpr modint operator--(int) {
    modint tmp(*this);
    --(*this);
    return tmp;
  }
  constexpr operator int() const { return (int)value; }
  constexpr operator ll() const { return value; }
};

MyPrinter &operator<<(MyPrinter &out, modint n) {
  out << n.value;
  return out;
}
DebugPrint &operator<<(DebugPrint &out, modint n) {
  cerr << n.value;
  return out;
}

constexpr modint pow(modint base, size_t exp) {
  modint res = 1;
  while (exp) {
    if (exp % 2)
      res *= base;
    base *= base;
    exp /= 2;
  }
  return res;
}

// O(r + log MOD)
modint choose(int n, int r) {
  chmin(r, n - r);
  if (r < 0)
    return modint(0);
  modint nu = 1, de = 1;
  rep(i, r) nu *= n - i, de *= i + 1;
  return nu / de;
}

int main() {
  int n = IN, s = IN;
  auto a = IN.vll(n);

  vector<modint> dp(s);
  dp[0] = modint(1);
  modint res = 0;
  rep(i, n) {
    if (a[i] < s)
      res += dp[s - a[i]] * modint(n - i);
    if (a[i] == s)
      res += modint(i + 1) * modint(n - i);
    repr(s1, a[i] + 1, s) { dp[s1] += dp[s1 - a[i]]; }
    if (a[i] < s) {
      dp[a[i]] += modint(i + 1);
    }
    rep(s1, s) debugos << dp[s1] << " ";
    debugos << newl << res << newl;
  }
  OUT(res);

  // vector<bitset<3005>> dp(s+1);
  // modint res = 0;
  // rep(i, n) repr(s1, a[i], s+1) {
  //   if (s1 < s) {
  //     if (s1 == a[i]) dp[s1][i] = 1;
  //     dp[s1] |= dp[s1-a[i]];
  //   } else {
  //     bitset<3005> st = dp[s-a[i]];
  //     if (s1 == a[i]) st[i] = 1;
  //     rep(j, i+1) if (st[j]) res += modint(j+1) * modint(n-i);
  //   }
  // }
  // OUT(res);
}

Fixed submission:
#ifdef LOCAL
#pragma GCC optimize("O0")
#else
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#pragma GCC target("avx")
#endif

#include <algorithm>
#include <bitset>
#include <cmath>
#include <functional>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <tuple>
#include <utility>
#include <vector>

using namespace std;

using ll = long long;
using VI = vector<int>;
using VVI = vector<vector<int>>;
using VLL = vector<ll>;
using VVLL = vector<vector<ll>>;
using VB = vector<bool>;
using VVB = vector<vector<bool>>;
using PII = pair<int, int>;
template <typename T> using minheap = priority_queue<T, vector<T>, greater<T>>;
const int INF = 1e9 + 7;
const ll INF_LL = (ll)1e18 + 7;

#define __overload3(_1, _2, _3, name, ...) name
#define rep(...)                                                               \
  __overload3(__VA_ARGS__, repFromUntil, repUntil, repeat)(__VA_ARGS__)
#define repeat(times) repFromUntil(__name, 0, times)
#define repUntil(name, times) repFromUntil(name, 0, times)
#define repFromUntil(name, from, until)                                        \
  for (int name = from, name##__until = (until); name < name##__until; name++)
#define repr(...)                                                              \
  __overload3(__VA_ARGS__, reprFromUntil, reprUntil, repeat)(__VA_ARGS__)
#define reprUntil(name, times) reprFromUntil(name, 0, times)
#define reprFromUntil(name, from, until)                                       \
  for (int name = until - 1, name##__from = (from); name >= name##__from;      \
       name--)

#define EXIT(out)                                                              \
  do {                                                                         \
    OUT(out);                                                                  \
    exit(0);                                                                   \
  } while (0)

#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
#define _1 first
#define _2 second

#define debug(v)                                                               \
  do {                                                                         \
    debugos << "L" << __LINE__ << " " << #v << " > ";                          \
    debugos << (v) << newl;                                                    \
  } while (0)
#define debugv(v)                                                              \
  do {                                                                         \
    debugos << "L" << __LINE__ << " " << #v << " > ";                          \
    for (auto e : (v)) {                                                       \
      debugos << e << " ";                                                     \
    }                                                                          \
    debugos << newl;                                                           \
  } while (0)
#define debuga(m, w)                                                           \
  do {                                                                         \
    debugos << "L" << __LINE__ << " " << #m << " > ";                          \
    for (int x = 0; x < (w); x++) {                                            \
      debugos << (m)[x] << " ";                                                \
    }                                                                          \
    debugos << newl;                                                           \
  } while (0)
#define debugaa(m, h, w)                                                       \
  do {                                                                         \
    debugos << "L" << __LINE__ << " " << #m << " > \n";                        \
    for (int y = 0; y < (h); y++) {                                            \
      for (int x = 0; x < (w); x++) {                                          \
        debugos << (m)[y][x] << " ";                                           \
      }                                                                        \
      debugos << newl;                                                         \
    }                                                                          \
  } while (0)

#define newl "\n"
constexpr int dr[] = {1, -1, 0, 0};
constexpr int dc[] = {0, 0, 1, -1};

bool inside(int r, int c, int H, int W) {
  return 0 <= r and r < H and 0 <= c and c < W;
}

template <typename T> bool chmin(T &var, T x) {
  if (var > x) {
    var = x;
    return true;
  } else
    return false;
}

template <typename T> bool chmax(T &var, T x) {
  if (var < x) {
    var = x;
    return true;
  } else
    return false;
}

template <typename T> struct minT {
  T operator()(T a, T b) { return min(a, b); }
};

template <typename T> struct maxT {
  T operator()(T a, T b) { return max(a, b); }
};

template <typename T> int sgn(T val) { return (T(0) < val) - (val < T(0)); }

ll power(ll e, int t, ll mod = INF_LL) {
  ll res = 1;
  while (t) {
    if (t & 1)
      res = (res * e) % mod;
    t >>= 1;
    e = (e * e) % mod;
  }
  return res;
}

template <typename T> T divceil(T, T);

template <typename T> T divfloor(T m, T d) {
  if (sgn(m) * sgn(d) >= 0)
    return m / d;
  else
    return -divceil(abs(m), abs(d));
}

template <typename T> T divceil(T m, T d) {
  if (m >= 0 and d > 0)
    return (m + d - 1) / d;
  else if (m < 0 and d < 0)
    return divceil(-m, -d);
  else
    return -divfloor(abs(m), abs(d));
}

template <typename T> vector<T> make_v(size_t a, T b) {
  return vector<T>(a, b);
}

template <typename... Ts> auto make_v(size_t a, Ts... ts) {
  return vector<decltype(make_v(ts...))>(a, make_v(ts...));
}

string operator*(const string &s, int times) {
  string res = "";
  rep(times) res += s;
  return res;
}

class MyScanner {
public:
  int offset = 0;
  template <typename T> void input_integer(T &var) {
    var = 0;
    T sign = 1;
    int cc = getchar();
    for (; cc < '0' || '9' < cc; cc = getchar())
      if (cc == '-')
        sign = -1;
    for (; '0' <= cc && cc <= '9'; cc = getchar())
      var = (var << 3) + (var << 1) + cc - '0';
    var = var * sign;
    var += offset;
  }
  int c() {
    char c;
    while (c = getchar(), c == ' ' or c == '\n')
      ;
    return c;
  }
  MyScanner &operator>>(char &var) {
    var = c();
    return *this;
  }
  MyScanner &operator>>(int &var) {
    input_integer<int>(var);
    return *this;
  }
  MyScanner &operator>>(ll &var) {
    input_integer<ll>(var);
    return *this;
  }
  MyScanner &operator>>(string &var) {
    int cc = getchar();
    for (; !isvisiblechar(cc); cc = getchar())
      ;
    for (; isvisiblechar(cc); cc = getchar())
      var.push_back(cc);
    return *this;
  }
  template <typename T> operator T() {
    T x;
    *this >> x;
    return x;
  }
  template <typename T> void operator()(T &t) { *this >> t; }
  template <typename T, typename... Ts> void operator()(T &t, Ts &...ts) {
    *this >> t;
    this->operator()(ts...);
  }
  template <typename Iter> void iter(Iter first, Iter last) {
    while (first != last)
      *this >> *first, first++;
  }
  VI vi(int n) {
    VI res(n);
    iter(all(res));
    return res;
  }
  VVI vvi(int n, int m) {
    VVI res(n);
    rep(i, n) res[i] = vi(m);
    return res;
  }
  VLL vll(int n) {
    VLL res(n);
    iter(all(res));
    return res;
  }
  VVLL vvll(int n, int m) {
    VVLL res(n);
    rep(i, n) res[i] = vll(m);
    return res;
  }
  template <typename T> vector<T> v(int n) {
    vector<T> res(n);
    iter(all(res));
    return res;
  }

private:
  int isvisiblechar(int c) { return 0x21 <= c && c <= 0x7E; }
} IN, IN1{-1};

class MyPrinter {
public:
  template <typename T> void output_integer(T var) {
    if (var == 0) {
      putchar('0');
      return;
    }
    if (var < 0)
      putchar('-'), var = -var;
    char stack[32];
    int stack_p = 0;
    while (var)
      stack[stack_p++] = '0' + (var % 10), var /= 10;
    while (stack_p)
      putchar(stack[--stack_p]);
  }
  MyPrinter &operator<<(char c) {
    putchar(c);
    return *this;
  }
  template <typename T> MyPrinter &operator<<(T var) {
    output_integer<T>(var);
    return *this;
  }
  MyPrinter &operator<<(char *str_p) {
    while (*str_p)
      putchar(*(str_p++));
    return *this;
  }
  MyPrinter &operator<<(const char *str_p) {
    while (*str_p)
      putchar(*(str_p++));
    return *this;
  }
  MyPrinter &operator<<(const string &str) {
    const char *p = str.c_str();
    const char *l = p + str.size();
    while (p < l)
      putchar(*p++);
    return *this;
  }
  // MyPrinter& operator<<(const modint& var) { output_integer<ll>(var.value);
  // return *this; }
  template <typename T> void operator()(T x) { *this << x << newl; }
  template <typename T, typename... Ts> void operator()(T x, Ts... xs) {
    *this << x << " ";
    this->operator()(xs...);
  }
  template <typename Iter> void iter(Iter s, Iter t) {
    if (s == t)
      *this << "\n";
    else {
      for (; s != t; s++) {
        *this << *s << " \n"[next(s, 1) == t];
      }
    }
  }
  template <typename Range> void range(const Range &r) {
    iter(begin(r), end(r));
  }
} OUT;

class DebugPrint {
public:
  template <typename T> DebugPrint &operator<<(const T &v) {
#ifdef LOCAL
    cerr << v;
#endif
    return *this;
  }
} debugos;
class modint;
constexpr modint pow(modint, size_t);
constexpr ll MOD = 998244353;

class modint {
public:
  ll value;

  constexpr modint(const ll x = 0) noexcept : value(x) {
    value %= MOD;
    if (value < 0)
      value += MOD;
  }
  constexpr bool operator==(const modint &rhs) { return value == rhs.value; }
  constexpr bool operator!=(const modint &rhs) { return value != rhs.value; }
  constexpr modint operator+(const modint &rhs) const {
    return modint(*this) += rhs;
  }
  constexpr modint operator-(const modint &rhs) const {
    return modint(*this) -= rhs;
  }
  constexpr modint operator*(const modint &rhs) const {
    return modint(*this) *= rhs;
  }
  constexpr modint operator/(const modint &rhs) const {
    return modint(*this) /= rhs;
  }
  constexpr modint &operator+=(const modint &rhs) {
    value += rhs.value;
    if (value >= MOD)
      value -= MOD;
    return *this;
  }
  constexpr modint &operator-=(const modint &rhs) {
    if (value < rhs.value)
      value += MOD;
    value -= rhs.value;
    return *this;
  }
  constexpr modint &operator*=(const modint &rhs) {
    value = value * rhs.value % MOD;
    return *this;
  }
  constexpr modint &operator/=(const modint &rhs) {
    return *this *= pow(rhs, MOD - 2);
  }
  constexpr modint &operator++() { return *this += 1; }
  constexpr modint operator++(int) {
    modint tmp(*this);
    ++(*this);
    return tmp;
  }
  constexpr modint &operator--() { return *this -= 1; }
  constexpr modint operator--(int) {
    modint tmp(*this);
    --(*this);
    return tmp;
  }
  constexpr operator int() const { return (int)value; }
  constexpr operator ll() const { return value; }
};

MyPrinter &operator<<(MyPrinter &out, modint n) {
  out << n.value;
  return out;
}
DebugPrint &operator<<(DebugPrint &out, modint n) {
  cerr << n.value;
  return out;
}

constexpr modint pow(modint base, size_t exp) {
  modint res = 1;
  while (exp) {
    if (exp % 2)
      res *= base;
    base *= base;
    exp /= 2;
  }
  return res;
}

// O(r + log MOD)
modint choose(int n, int r) {
  chmin(r, n - r);
  if (r < 0)
    return modint(0);
  modint nu = 1, de = 1;
  rep(i, r) nu *= n - i, de *= i + 1;
  return nu / de;
}

int main() {
  int n = IN, s = IN;
  auto a = IN.vll(n);

  vector<modint> dp(s);
  dp[0] = modint(1);
  modint res = 0;
  rep(i, n) {
    if (a[i] < s)
      res += dp[s - a[i]] * modint(n - i);
    if (a[i] == s)
      res += modint(i + 1) * modint(n - i);
    repr(s1, a[i] + 1, s) { dp[s1] += dp[s1 - a[i]]; }
    if (a[i] < s) {
      dp[a[i]] += modint(i + 1);
    }
  }
  OUT(res);

  // vector<bitset<3005>> dp(s+1);
  // modint res = 0;
  // rep(i, n) repr(s1, a[i], s+1) {
  //   if (s1 < s) {
  //     if (s1 == a[i]) dp[s1][i] = 1;
  //     dp[s1] |= dp[s1-a[i]];
  //   } else {
  //     bitset<3005> st = dp[s-a[i]];
  //     if (s1 == a[i]) st[i] = 1;
  //     rep(j, i+1) if (st[j]) res += modint(j+1) * modint(n-i);
  //   }
  // }
  // OUT(res);
}