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Problem solution · C++

Multipoint Evaluation on Geometric Sequence

Multipoint Evaluation on Geometric Sequence: a C++ solution using direct simulation. Learn the idea, check the complexity, and read the full code, with credit to NyaanNyaan Competitive Programming Library.

Technique
Direct simulation
Source
NyaanNyaan Competitive Programming Library
Length
51 lines
Start with the idea.

Try the problem first. If you get stuck, read the approach below, then write your own solution. The full code is at the bottom.

Approach

Direct simulation

For Multipoint Evaluation on Geometric Sequence, the implementation follows the problem’s operations directly while maintaining only the state needed for the next decision.

  1. Translate each rule into one explicit state update.
  2. Maintain the invariant after every processed item.
  3. Return the accumulated state once all relevant input has been handled.

Code notes

  • 51 lines of C++ from the credited upstream file yosupo-multipoint-evaluation-chirp-z.test.cpp.
  • The implementation keeps its working state in language-native values and containers.
  • 1 loop block detected.

Complexity

Count the number and nesting of passes over the input, then include the maintained containers in the memory estimate.

Check the problem constraints before deciding whether this complexity will pass.

Source

Code and credit

This code comes from NyaanNyaan Competitive Programming Library by NyaanNyaan and is used under the CC0-1.0 licence.

Open problem ↗Original source ↗
Full codeMultipoint Evaluation on Geometric Sequence · C++C++
Use this to learn the idea, then write your own version.
#define PROBLEM "https://judge.yosupo.jp/problem/multipoint_evaluation_on_geometric_sequence"//#include "../../template/template.hpp"//#include "../../misc/rng.hpp"//#include "../../ntt/chirp-z.hpp"//#include "../../fps/ntt-friendly-fps.hpp"#include "../../modint/montgomery-modint.hpp"#include "../../modulo/binomial.hpp"// #include "fps/arbitrary-fps.hpp"using namespace Nyaan;using mint = LazyMontgomeryModInt<998244353>;Binomial<mint> C;using fps = FormalPowerSeries<mint>; void test() {  rep(N, 50) rep(fdeg, 50) rep(W, 3) rep(A, 3) {    fps f(fdeg);    each(x, f) x = rng(0, 998244352);    fps ys1 = ChirpZ(f, W, N, A);    fps ys2(N);    rep(i, N) ys2[i] = f.eval(mint{W}.pow(i) * A);    if (ys1 != ys2) {      trc(N, fdeg, W, A);      trc(f);      trc(ys1);      trc(ys2);    }    assert(ys1 == ys2);  }  cerr << "OK" << endl;} void q() {  test();  int N, M, A, R, x;  in(N, M, A, R);  fps c(N);  rep(i, N) in(x), c[i] = x;  auto ps = ChirpZ(c, R, M, A);  out(ps);} void Nyaan::solve() {  int t = 1;  // in(t);  while (t--) q();}

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