Method inverse

Math/Subset Sum Problem.cpp:210–217

    return ans;
  }
  poly inverse(int n) const {  // 1 / p(x) % x^n, O(nlogn)
    assert(!is_zero()); assert(a[0] != 0);
    poly ans{mint(1) / a[0]};
    for(int i = 1; i < n; i *= 2) {
      ans = (ans * mint(2) - ans * ans * mod_xk(2 * i)).mod_xk(2 * i);
    }
    return ans.mod_xk(n);
  }
  poly log(int n) const { //ln p(x) mod x^n
    assert(a[0] == 1);
    return (differentiate().mod_xk(n) * inverse(n)).integrate().mod_xk(n);