bqi343 / cp-notebook

General Resources for Competitive Programming

README

Some material has been moved to the USACO Guide.

Notes

I am not planning to update:

• READMEs for most implementations
• USACO problem tables and solutions
  • Tables for recent USACO problems can be found here.

Since I frequently move stuff around, some READMEs may refer to files which no longer exist. If you would like to contribute, provide feedback, or encourage me to update something, please email me at [email protected] or submit a pull request. If you have a question, please read the entirety of "Resources" -> "Questions.md" first.

cp-notebook's Issues

Add ModInt Template Supporting Both int32 and int64

Like in tourist's solution for C from https://www.facebook.com/codingcompetitions/hacker-cup/2022/round-3/scoreboard

Fix Bug at Binary Search

Overflow will be happen at this line because if "hi= 2147483647" & "lo= 1" then the sum of "lo"+"hi" will be overflow.
So try to use the following formula to prevent overflow - - > " mid = lo + ((hi-lo)/2) "

I'll add PR.

https://github.com/bqi343/USACO/blob/26d1428ccd789e2b87c8e34f217f3d711d45fc35/Other%20Implementations/04%20-%20Sorting%20and%20Searching/Binary%20Search%20(4.3).cpp#L10

DirectedMST reconstruction crashes

With https://github.com/bqi343/USACO/blob/master/Implementations/content/graphs%20(12)/Misc/DirectedMST.h,

int main() {
	int n = 4, r = 1;
	vector<tuple<int, int, int>> data = {
		{0, 3, 27},
		{1, 2, 32},
		{2, 3, 25},
		{3, 0, 31},
		{3, 2, 23},
	};
	vector<Edge> edges;
	trav(e, data) {
		int a = get<0>(e);
		int b = get<1>(e);
		int w = get<2>(e);
		edges.push_back({a, b, w});
	}

	dmst(n, r, edges);
}

ends up with inEdge.s == -1 in the restore loop, causing it to misbehave and in practice later hit this assert: assert(i == r ? in[i].s == -1 : in[i].s == i);.

Found while looking into importing it into KACTL, through the directed MST stress test: https://github.com/kth-competitive-programming/kactl/blob/master/stress-tests/graph/DirectedMST.cpp. I don't understand the restoration algorithm well enough to know how to patch it.

Dropbox link outdated

The dropbox link in the third bullet point in README.md is outdated/broken.

Add Decremental Convex Hull?

Used for

• https://ncpc23.kattis.com/contests/ncpc23/problems/intertwined
• https://judge.yosupo.jp/problem/convex_layers

See https://codeforces.com/blog/entry/75929?#comment-607755 for an implementation

Add retrograd's Half-Plane Set

https://github.com/bicsi/kactl/blob/master/content/geometry/HalfplaneSet.h

Line container can solve CSA Squared Ends

In https://github.com/bqi343/USACO/blob/master/Implementations/content/data-structures/STL%20(5)/LCnew.h
said " CSA Squared Ends not working :("
but I managed to solve it using kactl line container...
My submission is here

Review Implementations

Probably worth maintaining a list of implementations included in the notebook here but not in KACTL. Check the corresponding implementation if:

• title is informative
• usage is clear
• impl has been validated
• distracting comments don't appear in the notebook
• impl has been compared against KACTL

Both:

• AhoCorasickFixed
• ModIntShort
• ModFact
• OrderStatisticTree
• Segment Tree
• Matrix
  • TODO: probably not worth including + and - in the notebook?
• LazySegmentTree
  • note: kactl's version is dynamic
• ModSqrt
• (uncommon) gp_hash_table
  • TODO: shorten the version here?
• linecontainer (old)
  • TODO: compare vs KACTL, compare vs new version?
• modmulll
• fastmod
• MillerRabin
• FactorFast
• Python3
• Simplex
• Integrate
• IntegrateAdaptive
• DSU
• RMQ
• LinearRecurrence
  • TODO: check if I actually remember what this does
• LCAjump
• treap
• Polynomial
• PolyInterpolate
• GaussianElimination
• FFT
• FFTMod
  • TODO: make this compatible with ModInt
• ModSum
• Euclid
• FracInterval
• CRT
• MinCostMaxFlow
  • TODO: recheck this
• GomoryHu
  • TODO: check that this works with Dinic
• MaxMatchFast
  • TODO: Usage / Indexing
• Hungarian
  • TODO: Usage / Indexing
• EulerWalk
  • TODO: Usage / Indexing
• SCCT
  • TODO: Usage / Indexing
• TwoSAT
  • TODO: Usage / Indexing
• BCC
  • TODO: Usage / Indexing
• MaximalCliques
• HLD
• LinkCutTree
• DirectedMST
• MatrixTree
• PointShort
  • OnSegment
• SegDist
• SegIsect
• Circle
• CircleIsect
• CircleTangents
• Circumcenter
• MinEnclosingCirc
• EdgeColor
• DelaunayFast
• PolyhedronVolume
• Point3D
• FastIO
• KMP
• Z
• PolyCenArea
• PolySaVol
• Manacher
• SuffixArray
• (Rare) SuffixTree
• HashRange
• LCArmq
• AngleCmp
• InPolygon
• Bellman Ford / Negative Cycle
• ConvexHull (Monotone Chain)
• HullDiameter
• LineHull
• CircleTangents
• ClosestPair
• PolygonArea
• PolygonCenter

Here Only:

• simple sieve
• persistent segment tree
• Multiplicative Prefix
  • TODO: remember what this does
• PrimeCnt
• ModArith
• DeBruijnSeq
• Nim Product
  • TODO: Usage
• matroid intersection
  • TODO: Usage
• ShermanMorrison
  • TODO: Usage
• polynomial inverse / log / exp
  • TODO: clean up
  • what's the difference between exp and expOld?
• Centroid Decomp
• Dinic
• GeneralMatchBlossom
• GeneralWeightedMatch
  • is the time complexity actually $O(N^3)$?
• ChordalGraphRecognition
• DominatorTree
• ComplexComp
• HalfPlaneIsect
• DelaunayIncremental
• Delaunay3
  • TODO: remove versions of Delaunay that are not preferred
• ManhattanMST
• Point3D
• Hull3DFast
• SuffixArrayLinear
  • TODO: check how fast this really is
• PalindromicTree
• (Rare) LyndonFactor
• (Rare) ReverseBurrowsWheeler
• (Rare) TandemRepeats
• (Rare) SuffixAutomaton
• (Rare) CircularLCS
• (Rare) SMAWK

KACTL Only:

• ContinuedFractions
• FracBinarySearch
• minRotation
• (unused) Angle
• (unused) sideOf
• (unused) PolygonCut
• (unused) PointInsideHull
• (unused) LineHullIntersection
• (easy) BIT
• (easy) union find rollback
• (easy) 2D rectangle sums
• (easy) BIT2D
• (easy) MoQueries
• (easy) PolyRoots
• (easy) golden section search
• (easy) hill climbing
• (unused) IntDeterminant
• (easy) SolveLinearBinary
• (never used) Tridiagonal
• (easy) fast subset transform
• (easy) modlog
• (never used) FastEratosthenes
• (easy) PhiFunction
• (unused) IntPerm
• (easy) Multinomial
• (easy) floyd warshall
• (easy) TopoSort
• (rarely used) PushRelabel
• (slow) EdmondsKarp
• (easy) DFS matching
• (easy) MinimumVertexCover
• (easy) CompressTree
• (easy) linearTransformation
• (unused) CirclePolyIntersection
• (easy) IntervalContainer
• (easy) IntervalCover
• (easy) ConstantIntervals
• (easy) Ternary Search
• (easy) LIS
• (slow) Hull3DSlow
• (unused) BumpAllocator
• (unused) SIMD
• (unused) KdTree
• (unused) Spherical Distance
• (unused) GlobalMinCut
• (unused) General Matching - Matrix Version
• (unused) MaximumClique

Use KACTL Edge Coloring

https://github.com/kth-competitive-programming/kactl/blob/main/content/graph/EdgeColoring.h

looks shorter than the current impl

Faster Version of RMQ?

iirc the current RMQ can be too slow on some suffix array problems

Fix ICPC notebook

font size:

kth-competitive-programming/kactl@3ad3b65

Hi

Hi Benjamin Congratulations for placing first in IOI. Can you share some of your templates and reading list? I really want to each plat this year in USACO.