Data Structures and Algorithms

Hub for #data-structures-and-algorithms

!scratch/leetcode/leetcode.md

Arrays and Hashing

Name	Brief	Updated	Tags
Counters	Counting contents of an array		note, data-structures, arrays-and-hashing
Map Lookups	Using a map to find an item in an array		note, data-structures, arrays-and-hashing
Prefix Postfix	Trick to track partial Summation answers		note, data-structures, arrays-and-hashing

Stack

Name	Brief	Updated	Tags
LIFO Stack	last in first out		note, data-structures, stack
Monotonic Stack	Always increasing/decreasing stack		note, stack, data-structures

Two Pointer

Name	Brief	Updated	Tags
Two Pointer Converging	For when you are looking for a pair/target		note, data-structures, two-pointer

Binary Search

Name	Brief	Updated	Tags
Binary Search Exact	Finding value in sorted array		note, data-structures, binary-search
Bisect Left-Right	Find leftmost or rightmost value in range		note, binary-search, data-structures
Bisect Range	Find the range of values		note, binary-search, data-structures
Predicate Search	TODO		note, binary-search

Sliding Window

Name	Brief	Updated	Tags
Fixed Sliding Window	For fixed size problems		note, data-structures, sliding-window
Variable Sliding Window	For finding a range that fulfills a condition		note, sliding-window

Trees

Name	Brief	Updated	Tags
Backtracking	Choose, explore, undo — DFS over partial solutions with pruning		note, data-structures, trees
Binary Search Tree (BST) Bisect Left-Right	Closest value (floor/ceiling) in a BST by walking the tree		note, trees, data-structures
Binary Search Tree (BST) Search Exact	Tree where left <= node <= right		note, data-structures, trees
Inorder traversal	Left → node → right;		note, data-structures, trees
Postorder traversal	Left → right → node;		note, data-structures, trees
Preorder traversal	Node → left → right;		note, data-structures, trees
Trie	Structure for text lookup		note, trees, data-structures

Linked List

Name	Brief	Updated	Tags
Floyd's Cycle Detection	For finding cycles and their start.		note, linked-list, data-structures
Gap Method	Sliding window for linked lists		note, data-structures, linked-list
Reverse Linked List	To reverse a node next node string		note, data-structures, linked-list

Heap

Name	Brief	Updated	Tags
Heap	Min/max always on top		note, heap, data-structures
Two heap	For keeping a running median		note, heap, data-structures

Graph

Name	Brief	Updated	Tags
Adjacency List	Graph+Map+Neighbors		note, graphs, data-structures
Breadth First Search	Checks each level before the next		note, data-structures, graphs
Depth First Search	Path traversal		note, graphs, data-structures
Dijkstra's Algorithm	Shortest distance algo		note, data-structures, graphs

Dynamic Programming

Name	Brief	Updated	Tags
Bottom up DP	Table based DP		note, data-structures, dp
Top down DP	Recursion based DP		note, data-structures, dp

Greedy

Name	Brief	Updated	Tags
Kadane's Algorithm	Max-sum contiguous subarray in O(n)		note, greedy, data-structures

Math

Name	Brief	Updated	Tags
Index digit in number	Get the i-th digit of an int without strings		note, data-structures, math
Integer length	Count digits of an int without strings		note, data-structures, math
K Nearest Neighbors	Nearest in XY plot		note, machine-learning, math, data-structures

State Machine

Name	Brief	Updated	Tags
State Machine	FSM		note, state-machine, data-structures

Sort

Name	Brief	Updated	Tags
Quick Sort			note, data-structures, data-structures-and-algorithms, sort

Resources

Colin Galen

Practice process: Solving a Leetcode Problem.
leetcode flashcards