Divide & Conquer

Canonical Example: MergeSort

Analysis of MergeSort

Solving Recurrence Relations

A Familiar Example: Binary Search

Example: Integer Multiplication

Improved Integer Multiplication

Example: Matrix Multiplication

Example: Closest Pair of Points

A Divide & Conquer Algorithm for Closest Pair of Points

We Don’t Have to Examine
All the Points

There are Just a Few Points To Check on the Other Side

Closest Pair Algorithm (Expanded)

Analysis

Example:
Gravitational N-Body Problem

Use an Octree

To Find the Force
on Particle p Due to Box B

Requirements

Results