🐬 Abbreviations

Short forms used inside notes. Titles and the sidebar use the full names.

Algorithms and Techniques

Short	Full form
BFS	Breadth-First Search
DFS	Depth-First Search
DP	Dynamic Programming
D&C	Divide and Conquer
CDQ	CDQ Divide and Conquer (after Chen Danqi)
CHT	Convex Hull Trick
SOS	Sum over Subsets (DP)
MITM	Meet in the Middle
IDA*	Iterative Deepening A*
MCTS	Monte Carlo Tree Search
UCT	Upper Confidence bounds applied to Trees
PBS	Parallel Binary Search
SA (heuristic)	Simulated Annealing
TSP	Travelling Salesman Problem
LIS	Longest Increasing Subsequence
LCS	Longest Common Subsequence
LCP	Longest Common Prefix
MEX	Minimum Excluded value
SG	Sprague–Grundy
MST	Minimum Spanning Tree
SPFA	Shortest Path Faster Algorithm
MCMF	Min Cost Max Flow
KMP	Knuth–Morris–Pratt
BWT	Burrows–Wheeler Transform
SA	Suffix Array
SAM	Suffix Automaton
SA-IS	Suffix Array by Induced Sorting
DC3	Difference Cover 3 (skew algorithm)
KMR	Karp–Miller–Rosenberg
FFT	Fast Fourier Transform
NTT	Number Theoretic Transform
DFT	Discrete Fourier Transform
FWHT	Fast Walsh–Hadamard Transform
FPS	Formal Power Series
OGF / EGF	Ordinary / Exponential Generating Function
BSGS	Baby-Step Giant-Step
CRT	Chinese Remainder Theorem
ECM	Elliptic Curve Method (Lenstra)
AKS	Agrawal–Kayal–Saxena primality test
DLX	Dancing Links (Algorithm X)
MPM	Malhotra–Pramodh Kumar–Maheshwari
SMAWK	Shor–Moran–Aggarwal–Wilber–Klawe
EDD	Earliest Due Date
SPT	Shortest Processing Time
LPT	Longest Processing Time

Data Structures

Short	Full form
DSU	Disjoint Set Union (union–find)
BIT	Binary Indexed Tree (Fenwick tree)
BST	Binary Search Tree
AVL	Adelson-Velsky–Landis tree
RMQ	Range Minimum Query
LCA	Lowest Common Ancestor
HLD	Heavy-Light Decomposition
ETT	Euler Tour Tree / Euler Tour Technique
LCT	Link-Cut Tree
BCT	Block-Cut Tree
SCC	Strongly Connected Components
BCC	Biconnected Components
DAG	Directed Acyclic Graph
ODT	Old Driver Tree (Chtholly tree)
PBDS	Policy-Based Data Structures (GNU)
STL	Standard Template Library
k-d tree	k-dimensional tree
LRU	Least Recently Used
FIFO / LIFO	First In First Out / Last In First Out

Math

Short	Full form
GCD / LCM	Greatest Common Divisor / Least Common Multiple
SPF	Smallest Prime Factor
GF($p$)	Galois (finite) field of order $p$
LP / ILP	Linear Programming / Integer Linear Programming
TU	Totally Unimodular
OEIS	On-Line Encyclopedia of Integer Sequences
AP / GP	Arithmetic / Geometric Progression
CCW / CW	Counter-Clockwise / Clockwise
MSB / LSB	Most / Least Significant Bit
XOR, AND, OR	bitwise exclusive or, and, or
RNG	Random Number Generator
EPS	epsilon (floating-point tolerance)

Complexity Theory

Short	Full form
P, NP	Polynomial time, Nondeterministic Polynomial time
NPC	NP-Complete
SAT / 2-SAT	Boolean Satisfiability / 2-variable clauses
FPT	Fixed-Parameter Tractable
PTAS / FPTAS	(Fully) Polynomial-Time Approximation Scheme
BPP, RP, ZPP	randomised complexity classes
PSPACE, EXPTIME	polynomial space, exponential time
DTM / NTM	Deterministic / Nondeterministic Turing Machine

Contests and Judges

Short	Full form
CP	Competitive Programming
ICPC	International Collegiate Programming Contest
WF	(ICPC) World Finals
IOI	International Olympiad in Informatics
CF	Codeforces
ABC / ARC / AGC	AtCoder Beginner / Regular / Grand Contest
CSES	Code Submission Evaluation System (problem set)
USACO	USA Computing Olympiad
SPOJ	Sphere Online Judge
KACTL	KTH Algorithm Competition Template Library
ACL	AtCoder Library
AC	Accepted
WA	Wrong Answer
TLE	Time Limit Exceeded
MLE	Memory Limit Exceeded
RE	Runtime Error
UB	Undefined Behaviour
I/O	Input / Output