From abb1bad0e018a14909faa2f5b0da5334aa00972f Mon Sep 17 00:00:00 2001
From: NehaKeshan <39170739+NehaKeshan@users.noreply.github.com>
Date: Fri, 27 Oct 2023 09:03:42 -0400
Subject: [PATCH] Update README.md

added overview of lists vs trees vs graphs
---
 lectures/17_trees_I/README.md | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/lectures/17_trees_I/README.md b/lectures/17_trees_I/README.md
index 26f3788..8c7e1f7 100644
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+++ b/lectures/17_trees_I/README.md
@@ -11,6 +11,11 @@
 - Implementation of ds_set class using binary search trees
 - In-order, pre-order, and post-order traversal
 
+## Overview: Lists vs Trees vs Graphs
+- Trees create a hierarchical organization of data, rather than the linear organization in linked lists (and arrays and vectors).
+- Binary search trees are the mechanism underlying maps & sets (and multimaps & multisets).
+- Mathematically speaking: A _graph_ is a set of vertices connected by edges. And a tree is a special graph that has no _cycles_. The edges that connect nodes in trees and graphs may be _directed_ or _undirected_.
+
 ## 17.1 Definition: Binary Trees
 
 - A binary tree (strictly speaking, a “rooted binary