From fcdf1422acd8757cffc8089f25713f0e92f4fdb0 Mon Sep 17 00:00:00 2001
From: bt3gl <138340846+bt3gl-google@users.noreply.github.com>
Date: Sun, 30 Jul 2023 16:13:15 -0700
Subject: [PATCH] Update README.md
---
trees_and_graphs/README.md | 42 +++++++++++++++++++++++++++++++++-----
1 file changed, 37 insertions(+), 5 deletions(-)
diff --git a/trees_and_graphs/README.md b/trees_and_graphs/README.md
index 36c5867..4559871 100644
--- a/trees_and_graphs/README.md
+++ b/trees_and_graphs/README.md
@@ -135,6 +135,17 @@ def postorder(self, root):
3. two items with an equal priority are dequeued based on their order in the queue
+
+
+----
+
+### n-ary tree
+
+
+
+* if a tree is a rooted tree in which each node has no more than N children, it's called N-ary tree.
+
+
----
@@ -143,14 +154,35 @@ def postorder(self, root):
-* a variant of n-ary tree in which characters are stored in each node
-* each path down the tree represents a word
-* the * nodes (null nodes) are often used to indicate complete words (usually represented by a special type of child) or a boolean flag that terminates the parent node
-* a node can have anywhere from 1 through alphabet_size + 1 child
-* can be used to store the entire english language for quick prefix lookup (O(k), where k is the length of the string)
+* tries, also called prefix tree, are a variant of n-ary tree in which characters are stored in each node.
+* each trie node represents a string (a prefix) and each path down the tree represents a word. note that not all the strings represented by trie nodes are meaningful.
+* the root is associated with the empty string.
+* the * nodes (null nodes) are often used to indicate complete words (usually represented by a special type of child) or a boolean flag that terminates the parent node.
+* a node can have anywhere from 1 through alphabet_size + 1 child.
+* can be used to store the entire english language for quick prefix lookup (O(k), where k is the length of the string). they are also widely used on autocompletes, spell checkers, etc.
+* tries structures can be represented by arrays and maps or trees.
+#### insertion
+
+
+
+* similar to a bst, when we insert a value to a trie, we need to decide which path to go depending on the target value we insert.
+* the root node needs to be initialized before you insert strings.
+
+
+
+#### search
+
+
+
+* all the descendants of a node have a common prefix of the string associated with that node, so it should be easy to search if there are any words in the trie that starts with the given prefix.
+* we go down the tree depending on the given prefix, once we cannot find the child node, the search fails.
+* we can also search for a specific word rather than a prefix, treating this word as a prefix and searching in the same way as above.
+* if the search succeeds, we need to check if the target word is only a prefix of words in the trie or if it's exactly a word (for example, by adding a boolean flag).
+
+
---