nt/factorizer.hpp

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Last update: 2024-11-09 00:49:07+00:00
Include: #include "nt/factorizer.hpp"

Depends on

prelude.hpp

Code

#pragma once
#include "prelude.hpp"

class factorizer {
 public:
  vector<int> lpf, ps;

  factorizer(int upto = 0) : lpf(upto + 1) {
    rep2(p, 2, lpf.size()) {
      if (lpf[p] == 0) lpf[p] = p, ps.push_back(p);
      for (auto q : ps) {
        if (q > lpf[p] || p * q > upto) break;
        lpf[p * q] = q;
      }
    }
  }

  int size() const { return lpf.size(); }
  vector<pair<int, int>> operator()(int n) const {
    vector<pair<int, int>> res;
    for (; n != 1; n /= lpf[n])
      if (!res.empty() && res.back().first == lpf[n]) res.back().second++;
      else res.emplace_back(lpf[n], 1);
    return res;
  }
};

#line 2 "prelude.hpp"
#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vi = vector<int>;
using vvi = vector<vector<int>>;
using vll = vector<ll>;
using vvll = vector<vector<ll>>;
using vc = vector<char>;
#define rep2(i, m, n) for (auto i = (m); i < (n); i++)
#define rep(i, n) rep2(i, 0, n)
#define repr2(i, m, n) for (auto i = (n); i-- > (m);)
#define repr(i, n) repr2(i, 0, n)
#define all(x) begin(x), end(x)
auto ndvec(int n, auto e) { return vector(n, e); }
auto ndvec(int n, auto ...e) { return vector(n, ndvec(e...)); }
auto comp_key(auto&& f) { return [&](auto&& a, auto&& b) { return f(a) < f(b); }; }
auto& max(const auto& a, const auto& b) { return a < b ? b : a; }
auto& min(const auto& a, const auto& b) { return b < a ? b : a; }
#if __cpp_lib_ranges
namespace R = std::ranges;
namespace V = std::views;
#endif
#line 3 "nt/factorizer.hpp"

class factorizer {
 public:
  vector<int> lpf, ps;

  factorizer(int upto = 0) : lpf(upto + 1) {
    rep2(p, 2, lpf.size()) {
      if (lpf[p] == 0) lpf[p] = p, ps.push_back(p);
      for (auto q : ps) {
        if (q > lpf[p] || p * q > upto) break;
        lpf[p * q] = q;
      }
    }
  }

  int size() const { return lpf.size(); }
  vector<pair<int, int>> operator()(int n) const {
    vector<pair<int, int>> res;
    for (; n != 1; n /= lpf[n])
      if (!res.empty() && res.back().first == lpf[n]) res.back().second++;
      else res.emplace_back(lpf[n], 1);
    return res;
  }
};