Enumerate supersets (Descending order)
(Mylib/Bit/enumerate_supersets_desc.cpp)

• View this file on GitHub
• Last update: 2021-04-23 23:44:44+09:00
• Link: View error logs on GitHub Actions

Operations

• for(int i : SupersetDesc(a, n)){...}
  • 大きさnの集合でaの上位集合であるものを降順に列挙する。

Requirements

Notes

Problems

References

• https://kimiyuki.net/blog/2017/07/16/enumerate-sets-with-bit-manipulation/
• https://jetbead.hatenablog.com/entry/20121202/1354406422
• https://ark4rk.hatenablog.com/entry/2018/03/07/230257
• https://primenumber.hatenadiary.jp/entry/2016/12/01/000000

Verified with

• test/aoj/ITP2_11_B/main.desc.test.cpp

Code

#pragma once

namespace haar_lib {
  template <typename Func>
  void enumerate_supersets_desc(int a, int n, const Func &f) {
    const int x = (1 << n) - 1, y = x ^ (a & x);
    for (int t = y;; t = (t - 1) & y) {
      if (not f(t | a)) break;
      if (t == 0) break;
    }
  }
}  // namespace haar_lib

#line 2 "Mylib/Bit/enumerate_supersets_desc.cpp"

namespace haar_lib {
  template <typename Func>
  void enumerate_supersets_desc(int a, int n, const Func &f) {
    const int x = (1 << n) - 1, y = x ^ (a & x);
    for (int t = y;; t = (t - 1) & y) {
      if (not f(t | a)) break;
      if (t == 0) break;
    }
  }
}  // namespace haar_lib

Back to top page