Method exp

Math/Subset Sum Problem.cpp:222–233

    return (differentiate().mod_xk(n) * inverse(n)).integrate().mod_xk(n);
  }
  poly exp(int n) const { //e ^ p(x) mod x^n
    if(is_zero()) return {1};
    assert(a[0] == 0);
    poly ans({1});
    int i = 1;
    while(i < n) {
      poly C = ans.log(2 * i).div_xk(i) - substr(i, 2 * i);
      ans -= (ans * C).mod_xk(i).mul_xk(i);
      i *= 2;
    }
    return ans.mod_xk(n);
  }
};
// number of subsets of an array of n elements having sum equal to k for each k from 1 to m
int32_t main() {