I don't know any

Sqrt decomposition

Data Structures(especially segment tree)

My favourite algorithm is SPFA (or FFT)

As a saying goes, "Stop learning useless algorithms, go and learn using binary search."

Even after a lot of practice I can say Binary search is something that still is quite difficult for me. My entire intuition for bs is if I can't solve it using greedy, dp or precomputation then it surely is bs.

Segment Tree

Simulation "algorithm". Especially in the CNOI competition system, a big simulation problem is really fun.

It doesn't require brain to think, but it does require too much time to debug. Today I just spend the first 3 hours in a 4-hour contest and get the 100 AC for this problem. (And used the rest hour to get the other 300pts) I feel like I was almost getting WA because the sample datas (just like pretests in CF, we can't get feedback of submissions in CNOI) were much too weak.

Honestly, simulating algorithms is a time-consuming and thankless approach. Once you make a small mistake in hundreds of lines of code but fail to find it, or even didn't plan to find any because you have passed the sample, then you are all done.

But why, you can't say that you can't solve it because you haven't learned enough, the hardest part in my 400-line code is calculate LCA in O(logn). Exciting and annoying, but I just like it best.

DINIC Network Flow of course!!!!

DP or Tarjan :)

MO algorithm

DP and sqrt decomposition

SortedList

Network flow. Problems needs skill, and the proof of correctness of Ford-Fulkerson method and complexity of Highest Label Preflow Push are ingenious. Also like string-related automatons.

Binary search

binary search.

BST, especially Balanced Tree.

In CNOI system, the most common Balanced Tree is FHQ Treap ( a special implementation of Treap which is easy to understand and debug ) , and Splay is seen often, too. But I enjoy the moment that my Weight Balanced Leafy Tree gets better speed than other's Treap or Splay.

There's many kinds of Balanced Tree and each of them has their own peculiarity. Some is easy to write, and others are the basis of other algorithms, such as Splay for Link-Cut Tree, and it's fun to learn all of them.

But could data structures be called "algorithm"? Actually I ofter tell them apart. I choose a ds just because I saw someone do that in the comments section.

KMP SEARCH

My favorite algorithm is sort

see in this blog About the limits of the sorting problems.

kruskal MST

I wonder why no people replied me.

Only algo I know is Sieve

i only love data structure!

kadane's algorithm for sure!!

Hashing Algorithm <3

Binary Search

Algorithm that I make while solving 1000 rated problems:

vjudje algorithms

does dfs count?

I think FFT is a beautiful algorithm, but unfortunately I've never been good enough to actually use it to solve anything :)

Kruskal Reconstruction Tree and Treap

ternary search

Probably greedy algorithm or binary search

DSU dinic mcmf

bogosort

Fandalma's algorithm

For Loop

Not really an algorithm, but Sprague-Grundy is pretty beautiful :)

Lee(aka bfs on grid)

Ad Hoc

Z — algo

Iterative Segment tree — It is short to implement and you can cheese a lot of stuff with it since it is pretty light

Thx for everyone's comments! I've never even heard of some of them

If statement

I'm a boruvka enjoyer. It clears prim and kruskal

hashing !

Honestly, Programming is the best algorithm that everyone uses. You can't tell me that you don't know this algorithm. And to solve every problem, you need this insanely hard algorithm.

Edit: this is my second favourite algo:

i++;

(surely this is the hardest algo ever)

Sieve of Eratosthenes

Surprised no one has mentioned Fenwick/binary indexed tree yet :)

dp or data structures.

binary search an dp <3 !

link-cut tree! the implementation is so elegant！

Haha It must be Dijkstra.Few years ago I spent a whole afternoon learning it(also how to store a graph with linked list) with my friends.I enjoy and miss that time.

of course, florrfloor sum.

Dunno why guys, but I love using CBT on problems.

SATT AAAT and ETT

simulated annealing and binary search

binary search and sieve I like both of them

parallel binary search, FFT, sqrt decomposition, centroid decomposition and math-related dp probably

Data structures [Segment Tree — sparse table] & Graphs and Trees & Binary Search and Prefix arrays

KMP

PST on HLD with FFT implemented by NTT with CRT to maintain CHT calculating MCF for MCC with SCC on MST using BIT to store LCT and D&C on KMP on FPS to optimize SAM for BCC evaluating PIE why is there CHT twice based on ODT with GHT maintaining KDT to calculate MVC, MBM, and MIS on LIS-SOS induced graph with ETT and CZT on each node with SEC on each hyperplane to do ILP on a SBT with CPP instances using PHP optimized by PBS using HMT, with LCP on WMI as universe done with MPM to maintain AAT with OST on RSA numbers for WBG-EGT counting on TCC of resulting TCP for RBT with IST on each node to do EST for DLX with PET pruning

dsu and z function cuz thats all i know