RBST

Randomized Binary Search Tree

• ABC170 E Commentary on.

  • Ordered multisets can be processed quickly by using C++ multisets, etc.

  • and therefore, what is the equivalent of multiset in C++ in Python? and the topic was raised - multiset in Python There are many cases where you can get by with heapq.
    • Python does not have equilibrium binary tree in the standard library
      • I felt like it would be a good idea to have it as my own library...

• Implementations that make nodes as objects are generally bad.

  • Because of the high cost of generating objects.
  • Implement in arrays and make with the policy to compile in numba.

• AC on ABC170E

--- Development

• C++ implementation ported to Python
  • Summary of data structures that can retrieve the kth value fast - such as BIT upper binary search and equilibrium binary search tree - Qiita, ported naively from
  • https://github.com/nishio/atcoder/blob/master/memo/rbst_normal.py
• Replace ABC170 E implementation in Fennic tree with RBST and verify AC in all test codes
  • Implementation in phoenix tree 4.83sec
  • Implementation in RBST 105.47sec
  • 20 times slower
• Remove class
  • 67.01sec
  • About 60% faster.
• Remove recurrence call and compile with [numba
  • 10.13sec
• Sequential addition in list changed to batch allocation in np.array
  • 4.60sec

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