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Kattis

ProblemKattis difficultyAlgorithm implemented
tsp9.8MST preorder approximation
vedurspa9.6Exact least-squares regression
atrivialpursuit9.1Prime factorisation and inclusion-exclusion
basincity8.2Kernelisation and branching
dimensionalanalysis8.1Exact Gaussian elimination
doublets7.8Wildcard indexing and BFS
anothersubstringqueryproblem7.7Suffix array, persistent segment tree
magicsequence7.4Radix sort
bigfactoring7.2Pollard rho and primality certificates
palindromes7.2Manacher’s algorithm, Fenwick sweeps
committeeassignment7.0Backtracking graph colouring
kingpinescape7.0DFS leaf pairing
securitybadge7.0Interval compression and graph reachability
helpfulcurrents6.9Grid-DAG path counting
roadtimes6.9Floyd–Warshall and linear programming
numbersetshard6.7Prime sieve and union–find
sumsets6.7Meet-in-the-middle pair-sum hashing
indoorienteering6.6Meet-in-the-middle tour search
worstweather6.6Binary search and range-max queries
catenyms6.5Hierholzer’s Euler trail
isahasa6.4Bitset transitive closure
antiarithmetic6.3Mirrored bitset scan
largesttriangle6.3Convex hull and rotating calipers
nonnegpartsums6.3Prefix sums and monotone deque
bitwise6.2Bitwise greedy, next-cut pointers
derangementrotations6.2GCD counting and modular exponentiation
darkness6.0Illumination filtering and minimum cut
xormax5.9Binary linear basis
knapsack25.8Residue-class cyclic relaxation
farmingmars5.7Mo’s offline range queries
bilateral5.6Bipartite matching and vertex cover
addemup5.5Sorting and binary search
baza5.5Trie with prefix counts
cudak5.4Digit dynamic programming
intersectingrectangles5.4Plane sweep with AVL trees
selfbalancingbst5.3Persistent order-statistic red-black trees
tugofwar5.3Cardinality-aware subset-sum dynamic programming
joggers5.2Greedy tree vertex cover (BFS order, bottom-up)
closestpair25.2Divide-and-conquer closest pair
loopycabdrivers5.1Strongly connected components
remainderreminder5.1Volume enumeration and generalised CRT
chesstournament5.0Union–find and topological sorting
slowleak5.0Floyd–Warshall and Dijkstra
zapis5.0Interval dynamic programming
hashing4.9Polynomial prefix hashing
candydistribution4.7Extended Euclidean algorithm
canonical4.7Coin-change dynamic programming
gcpc4.7Order-statistic AVL tree
segmentintersection4.7Exact cross-product intersection tests
primepower4.6Sieve and modular exponentiation
booking4.5Sorted event sweep
cardhand4.4Suit enumeration and LCS
equationsolver4.4Certified Gaussian elimination
polymul24.4Split-coefficient FFT convolution
suffixsorting4.4Prefix-doubling suffix array
intervalcover4.3Greedy interval covering
yatp4.3Centroid decomposition, Li Chao trees
cuboidslicinggame4.2Sprague–Grundy dynamic programming
excavatorexpedition4.1DAG longest-path dynamic programming
fulltank4.1Dijkstra on city–fuel states with a Fibonacci heap
stringmultimatching4.1Aho–Corasick multi-pattern matching
kattissquest4.0Van Emde Boas tree, heaps
ultraquicksort4.0Merge-sort inversion counting
bracketsequence3.9Stack-based expression evaluation
water3.9Incremental Edmonds–Karp flow
purplerain3.8Prefix-sum extrema
joinstrings3.6Linked-list splicing
canvas3.5Huffman-style greedy merging
pascal3.5Smallest-prime-factor trial division
timing3.5Certified floating-point simulation
bst3.4Red-black tree neighbour queries
chatter3.4Weighted-union linked lists
closestpair13.4Bucket sort and geometric sweep
knigsoftheforest3.4Max-heap tournament simulation
dirtydriving3.3Sorting and greedy scan
longincsubseq3.3Patience sorting with binary search
stringmatching3.3Knuth–Morris–Pratt string matching
arbitrage3.2Max-product Floyd–Warshall
knapsack3.10/1 knapsack dynamic programming
communicationssatellite2.9Dense Prim’s algorithm
mazemovement2.8Push–relabel maximum flow
median2.8Randomised quickselect
roberthood2.8Convex hull and rotating calipers
allpairspath2.7Johnson’s all-pairs shortest paths
relatives2.7Euler’s totient by trial division
generalchineseremainder2.6Generalised Chinese remainder theorem
unionfind2.6Union by rank, path compression
satisfiability2.6Exhaustive truth-assignment search
minspantree2.5Kruskal’s algorithm
convexhull2.4Andrew’s monotone chain
plot2.4Horner evaluation and forward differences
bank2.3Greedy scheduling with disjoint sets
ada2.2Newton forward differences
babelfish2.0FKS perfect hashing
shortestpath32.0Bellman–Ford with negative-cycle propagation
shortestpath12.0Dijkstra with binary heap
polygonarea1.8Shoelace formula
polymul11.7Schoolbook polynomial convolution
oddmanout1.5XOR reduction
cold1.2Single-pass counting