Data Structures

Stack

Last In First Out (LIFO)

push: add item to top of stack pop: remove and return item from top of stack peek: return item from top of stack size: return the len of the stack

Queue

First in First Out (FIFO)

push: add to tail of queue pop: remove and return the oldest item (head) peek: return the item in front of queue size: return the len of the queue

Linked List

Have a self.head and optionally a self.tail. self.head.next refers to next node if 1 node then self.head and self.tail is the same.

Graph

Preorder traversal

• Append val to list
• Recusively go down left
• Recursively go down right
• return list

Postorder traversal

• recursively go down left
• recursively go down right
• append val to list
• return list

Inorder

• recursively go down left
• append val to list
• recurisvely go down right
• return list

Trie

A dictionary made of nested objects. Can help find words

{
	"h": {
		"e": {
			"l": {
				"l": {
					"o": {
						"": True
					}
				},
				"p": {
					"": True
				}
			}
		},
		"i": {
			"": True
		}
	}
	"w": {
		"o": {
			"r":{
				"l":{
					"d":{
						"": True
					}
				}
			}
			"w":{
				"": True
			}
		}
	}
}

Can be used for autofills