Submission #1554766

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Source Code Expand

#include<bits/stdc++.h>

using namespace std;

typedef complex< double > C;
const double PI = acos(-1);

vector< C > DFT(vector< C > &f, int dir)
{
  if(f.size() == 1) return (f);
  auto n = f.size(), mid = f.size() >> 1;
  vector< C > f0(mid), f1(mid);
  for(int i = 0; i < mid; i++) f0[i] = f[2 * i + 0];
  for(int i = 0; i < mid; i++) f1[i] = f[2 * i + 1];
  f0 = DFT(f0, dir), f1 = DFT(f1, dir);
  C zeta = polar(1.0, 2 * PI * dir / n), pow_zeta(1.0);
  for(int i = 0; i < n; i++) {
    f[i] = f0[i < mid ? i : i - mid] + pow_zeta * f1[i < mid ? i : i - mid];
    pow_zeta *= zeta;
  }
  return (f);
}

vector< C > Multiply(vector< C > &g, vector< C > &h)
{
  int sz = 1;
  while(sz <= g.size() + h.size()) sz *= 2;
  g.resize(sz), h.resize(sz);
  auto gg = DFT(g, 1), hh = DFT(h, 1);
  vector< C > ff(sz);
  for(int i = 0; i < sz; i++) ff[i] = gg[i] * hh[i];
  auto get = DFT(ff, -1);
  for(int i = 0; i < sz; i++) get[i] /= sz;
  return (get);
}


int main()
{
  int N;
  cin >> N;
  vector< C > a(N + 1), b(N + 1);
  for(int i = 1; i <= N; i++) cin >> a[i] >> b[i];
  auto c = Multiply(a, b);
  for(int i = 1; i <= 2 * N; i++) cout << (int) round(real(c[i])) << endl;
}

Submission Info

Judge Result