代码

// luogu-judger-enable-o2
// =================================
//   author: memset0
//   date: 2019.07.07 23:10:06
//   website: https://memset0.cn/
// =================================
#include <bits/stdc++.h>
#define ll long long
#define rep(i, l, r) for (int (i) = (l), __lim = (r); (i) <= __lim; (i)++)
#define for_each(i, a) for (size_t i = 0, __lim = a.size(); i < __lim; ++i)
namespace ringo {

template <class T> inline void read(T &x) {
  x = 0; char c = getchar(); bool f = 0;
  while (!isdigit(c)) f ^= c == '-', c = getchar();
  while (isdigit(c)) x = x * 10 + c - '0', c = getchar();
  if (f) x = -x;
}
template <class T> inline void print(T x) {
  if (x < 0) putchar('-'), x = -x;
  if (x > 9) print(x / 10);
  putchar('0' + x % 10);
}
template <class T> inline void print(T x, char c) { print(x), putchar(c); }
template <class T> inline void print(T a, int l, int r, std::string s = "") {
  if (s != "") std::cout << s << ": ";
  for (int i = l; i <= r; i++) print(a[i], " \n"[i == r]);
}

const int N = 1e6 + 10, mod = 998244353;
int n, m;

inline int dec(int a, int b) { a -= b; return a + ((a >> 31) & mod); }
inline int inc(int a, int b) { a += b - mod; return a + ((a >> 31) & mod); }
inline int mul(int a, int b) { return static_cast<ll>(a) * b % mod; }
inline int inv(int x) { return x < 2 ? 1 : mul(mod - mod / x, inv(mod % x)); }
inline int fpow(int a, int b) { int s = 1; for (; b; b >>= 1, a = mul(a, a)) if (b & 1) s = mul(s, a); return s; }

struct poly : std::vector<int> {
  using std::vector<int>::vector;
  inline void in() { for (auto &x : *this) read(x); }
  inline void out() const { for (auto x : *this) print(x, ' '); putchar('\n'); }
} f, g;

int w[N << 2], rev[N << 2];
int init(int len) {
  int lim = 1, k = 0; while (lim < len) lim <<= 1, ++k;
  for (int i = 0; i < lim; i++) rev[i] = (rev[i >> 1] >> 1) | ((i & 1) << (k - 1));
  static int base_len = 1;
  for (int len = base_len, wn; len < lim; base_len = len <<= 1) {
    wn = fpow(3, (mod - 1) / (len << 1)), w[len] = 1;
    for (int i = 1; i < len; i++) w[i + len] = mul(w[i + len - 1], wn);
  } return lim;
}

void dft(poly &a, int lim) {
  a.resize(lim);
  for (int i = 0; i < lim; i++) if (i < rev[i]) std::swap(a[i], a[rev[i]]);
  if (lim > 1) {
    for (int i = 0; i < lim; i += 2) {
      int x = a[i], y = a[i + 1];
      a[i] = inc(x, y), a[i + 1] = dec(x, y);
    }
  }
  for (int len = 2; len < lim; len <<= 1)
    for (int i = 0; i < lim; i += (len << 1))
      for (int j = 0; j < len; j++) {
        int x = a[i + j], y = mul(w[j + len], a[i + j + len]);
        a[i + j] = inc(x, y), a[i + j + len] = dec(x, y);
      }
}

void idft(poly &a, int lim) {
  a.resize(lim), std::reverse(&a[1], &a[lim]);
  dft(a, lim); int inv_lim = inv(lim);
  for (int i = 0; i < lim; i++) a[i] = mul(a[i], inv_lim);
}

poly mul(const poly &f, const poly &g, int len = -1) {
  static poly a, b; a = f, b = g;
  int lim = init(f.size() + g.size() - 1);
  dft(a, lim), dft(b, lim);
  for (int i = 0; i < lim; i++) a[i] = mul(a[i], b[i]);
  idft(a, lim); a.resize(~len ? len : f.size() + g.size() - 1);
  return a;
}

void main() {
  read(n), read(m), f.resize(n + 1), g.resize(m + 1);
  f.in(), g.in(), mul(f, g).out();
}

} signed main() {
#ifdef memset0
  freopen("1.in", "r", stdin);
#endif
  return ringo::main(), 0;
}

评测结果