MetaHackerCup-2024

• Python3 solutions of Meta Hacker Cup 2024. Solution begins with * means it will get TLE in the largest data set.
• Total computation amount > 10^8, which is not friendly for Python3 to solve in 5 ~ 15 seconds. A 6-minute timer is set for uploading the result this year.
• A problem was marked as Very Hard means that it was an unsolved one during the contest and may not be that difficult.

Rounds

• Hacker Cup 2023
• Practice Round
• Round 1
• Round 2
• Round 3
• Final Round
• Hacker Cup 2025

Practice Round

#	Title	Solution	Time	Space	Difficulty	Tag	Note
A	Walk the Line	Python3	O(1)	O(1)	Easy		Greedy
B	Line by Line	Python3	O(1)	O(1)	Easy		Math
C	Fall in Line	Python3	O(K * N)	O(1)	Medium		Randomized Algorithm
D1	Line of Delivery (Part 1)	Python3	O(NlogN)	O(1)	Medium		Sort
D2	Line of Delivery (Part 2)	Python3	O(NlogN)	O(1)	Hard		Sort

Round 1

#	Title	Solution	Time	Space	Difficulty	Tag	Note
A	Subsonic Subway	Python3	O(N)	O(1)	Easy		Math
B	Prime Subtractorization	Python3	precompute: O(MAX_N) runtime: O(1)	O(MAX_N)	Medium		Number Theory, Linear Sieve of Eratosthenes, DP
C	Substantial Losses	Python3	O(1)	O(1)	Medium		Expected Value
D	Substitution Cipher	Python3	O(N)	O(1)	Hard		Greedy, DP
E	Wildcard Submissions	PyPy3	O(N * L * S)	O(L * S)	Hard		DP, Inclusion-Exclusion Principle

Round 2

#	Title	Solution	Time	Space	Difficulty	Tag	Note
A1	Cottontail Climb (Part 1)	Python3	O(285)	O(45)	Easy		Precomputation
A2	Cottontail Climb (Part 2)	PyPy3	precompute: O(17 * 73025424) runtime: O(73025424)	O(73025424)	Easy		Precomputation, Backtracking
B	Four in a Burrow	PyPy3	O((R * C) * (R + 1)^C)	O(C * (R + 1)^C)	Medium		BFS
C	Bunny Hopscotch	PyPy3	O((R * C * log(min(R, C))) * log(max(R, C)))	O(R * C)	Medium		Binary Search, Two Pointers, Sliding Window, BIT, Fenwick Tree
D	Splitting Hares	Python3	O(N + MAX_W^2)	O(N + MAX_W)	Hard		Greedy, DP, Backtracing

Round 3

#	Title	Solution	Time	Space	Difficulty	Tag	Note
A	Set, Cover	Python3	O(N^2)	O(N)	Easy		Array
B	Least Common Ancestor	Python3	O(N * (logN)^2)	O(N)	Easy		Sort, DFS, Sorted List, Freq Table, Small-to-Large Merging
C	Coin Change	Python3	O(min(N, THRESHOLD))	O(1)	Hard		Expected Value, Harmonic Series, Euler's Constant
D	Min-flow Max-cut	Python3	O(N * logN * logM)	O(N)	Hard		DFS, Treap, Prefix Sum, Small-to-Large Merging
E1	All Triplets Shortest Path (Part 1)	Python3	O(N)	O(N)	Medium		Graph, Floyd-Warshall Algorithm
E2	All Triplets Shortest Path (Part 2)	Python3	O(N)	O(N)	Medium		Graph, Floyd-Warshall Algorithm

Final Round

You can relive the magic of the 2024 Hacker Cup World Finals by watching the Live Stream Recording of the announcement of winners.

#	Title	Solution	Time	Space	Difficulty	Tag	Note
A	Duplicate Order	Python3	O(N + min(M1, M2) + H^2)	O(N + min(M1, M2) + H)	Easy		Combinatorics, Prefix Sum, Fast Exponentiation
B	Distributed Server	Python3	O((R + C)^2 * (R * C)^3)	O(R * C)	Easy		Binary Search, Max Flow, Dinic's Algorithm
C	Chicken Tender	Python3	O(N^2 * logR)	O(N)	Medium		Ternary Search, Geometry
D	Sushi Platter	Python3	O(N^3 * MAX_A + M! * ((M - 1) * 2^(M - 1)))	O(N^2 * MAX_A)	Medium		Connected Component DP, Prefix Sum, Permutation, Bitmasks
E	Snake Cover	Python3	O(M)	O(M)	Medium		Simulation, Data Structures, Queue, Mono Deque
F	Pizza Broiler	Python3	O(W + NlogW)	O(W)	Hard		Geometry, Binary Search, Prefix Sum, Count Lattices