---
id: bin-jump
title: "Binary Jumping"
author: Benjamin Qi
description: Introduces the problems of finding level ancestors in a tree and computing the lowest common ancestors.
---

<problems-list>
    <problem name="Planet Queries I" cses="1750" difficulty="Easy" tags={["Binary Jumping"]}>
    </problem>
    <problem name="Company Queries I" cses="1687" difficulty="Easy" tags={["Binary Jumping"]}>
    </problem>
    <problem name="Company Queries II" cses="1688" difficulty="Easy" tags={["LCA"]}>
    </problem>
</problems-list>

## Binary Jumping

## Lowest Common Ancestor

### Tutorial

 - CPH 18.1, 18.3
 - [cp-algorithms](https://cp-algorithms.com/)

<optional-content title="Improvements">

  - [CF: $O(\log N)$ queries and $O(N)$ memory](https://codeforces.com/blog/entry/74847)
  - [Wikipedia: $O(1)$ queries and $O(N)$ preprocessing time](https://en.wikipedia.org/wiki/Level_ancestor_problem#Ladder_algorithm)
    - though explanation is not the greatest

</optional-content>

### Problems

<problems-list>
    <problem name="Distance Queries" cses="1135" difficulty="Easy" tags={["LCA"]}>
    </problem>
    <problem name="Plat - Max Flow" usaco="576" difficulty="Easy" tags={["LCA"]}>
    </problem>
    <problem name="Root LCA Queries" csa="root-lca-queries" difficulty="Normal" tags={["LCA"]}>
    </problem>
    <problem name="Planets Queries II" cses="1160" difficulty="Normal" tags={["LCA"]}>
    </problem>
    <problem name="Plat - Disruption" usaco="842" difficulty="Normal" tags={["LCA"]}>
    </problem>
    <problem name="Hot & Cold" dmoj="bts17p7" difficulty="Normal" tags={["LCA"]}>
    </problem>
    <problem name="Plat - Tree Boxes" usaco="948" difficulty="Hard" tags={["LCA"]}>
      - interactive!!
    </problem>
    <problem name="Plat - Newbarns" usaco="817" difficulty="Hard" tags={["Diameter"]}>
      Copy of [CF Brain Network "Hard"](https://codeforces.com/contest/690/problem/C3)
    </problem>
    <problem name="Plat - Gathering" usaco="866" difficulty="Hard" tags={["LCA"]}>
      - interactive!!
    </problem>
    <problem name="Plat - Exercise" usaco="901" difficulty="Very Hard" tags={["LCA"]}>
    </problem>
</problems-list>