Lore
This was an annual competition hosted by a big tech company that had the same winner for 8 years in its history, 7 of which were in a row.
What is Google Code Jam?
This algorithm allows you to find the shortest path from a source vertex to all other vertices in a directed, weighted graph with non-negative weights.
What is Dijkstra's algorithm?
This is the greatest prime factor of 22027 - 22023.
What is 5?
The goal of this program is to add 2 numbers a and b, with constraints -100 <= a, b <= 100. This is a test case which hacks this program.
What is a = -1, b = 0?
This is an array of 5 positive integers with sum of 46.
What is [9, 9, 9, 9, 10]?
This is a Japanese-based competitive programming platform (in)famous for its ad hoc style problems.
What is AtCoder?
This algorithm allows you to find the convex hull of a set of points in O(n log n) time by sorting the points radially with respect to the bottommost point and maintaining a stack.
What is Graham Scan?
Gretchen has 10 indistinguishable rocks to be grouped into three different piles. All of the piles must have at least one rock, and the order of the piles does not matter. This is the number of different ways Gretchen can group her rocks.
What is 8?
The goal of this program is to sort an integer array a of length n. Constraints: 1 <= n <= 105, 1 <= ai <= 109, n is divisible by 3. This is an array that this program does not properly sort.
What is [3, 2, 1]?
This is an array of 5 positive integers where every subset of integers has a distinct sum.
What is [1, 2, 4, 8, 16]?
As of April 13, 2023, this is the highest rated user on Codeforces.
Who is jiangly?
This variation of the Fast Fourier Transform allows you to multiply two polynomials of sizes a and b with a + b - 1 <= 2k under a prime modulus of the form p = c2k + 1 (e.g. 998244353) in O(n log n) time.
What is Number Theoretic Transform?
This is the sum of all values of x that satisfy the equation x4 - 5x2 + 4 = 4.
What is 0?
The goal of this program is to detect if an undirected graph of n vertices contains no cycles. Constraints: 1 <= n <= 105, all vertex IDs are between 0 and n - 1 inclusive, the adjacency list describes a valid undirected graph. This is a test case which hacks this program.
What is a graph consisting of two components, one which is a 4 vertex cycle and the other is an isolated vertex?
This is a graph of at least 4 vertices, every vertex has degree at least 3, but the graph is not 2-edge-connected (there exists an edge I can remove to disconnect the graph).
What is the graph consisting of two instances of K4 joined by a single edge?
As of April 13, 2023, this is the name of the problem with the second most number of solves on Codeforces.
What is Way Too Long Words?
This technique originated from a CTSC (China Team Selection Competition) paper, was made well-known to the greater CP community via a CF blog in 2018, and detailed a technique on how to solve problems like "range ckmin, range query sum" in O(n log2 n).
What is Segment Tree Beats?
Ted mistakenly wrote 2m * sqrt(1/4096) as 2 * [mth root](1/4096). This is the sum of all real numbers m for which both are equal.
What is 7?
The goal of this program is to read in several arrays and check if each of them are non-decreasing arrays. Constraints: numTests <= 10, 1 <= n <= 105, 1 <= ai <= 109. This is a series of test cases which hacks this program.
What is a test set of 2 arrays, the first is [1, 2, 3], the second is [1, 4]?
This is a permutation of 1, 2, .., 8 where no subarray has bitwise xor of its elements = 0.
What is [1, 2, 4, 3, 6, 7, 8, 5]?
This is the number of times Georgia Tech has qualified to the ICPC World Finals in history.
What is 11?
This is the complexity of an almost-linear time algorithm for max flow and min-cost flow on a directed flow network of m edges for integral demands, costs, and capacities published by a former Georgia Tech professor in April of last year.
What is m1 + o(1)?
Suppose that 13 cards numbered 1, 2, 3, ..., 13 are arranged in a row. The task is to pick them up in numerically increasing order, working repeatedly from left to right. For example, if the cards were [7, 11, 8, 6, 4, 5, 9, 12, 1, 13, 10, 2, 3] in that order, then cards 1, 2, 3 are picked up on the first pass, 4 and 5 on the second pass, 6 on the third pass, 7, 8, 9, 10 on the fourth pass, and 11, 12, 13 on the fifth pass. This is the number of orderings out of the 13! total such that all 13 cards are picked up in exactly two passes.
What is 8178?
The goal of this program is to compute the nth Fibonacci number mod m. The Fibonacci sequence is defined recursively as F0 = 0, F1 = 1, Fn = Fn-1 + Fn-2. Constraints: 1 <= n <= 105, 1 <= m <= 109. This is a test case which hacks this program.
What is n = 1, m = 1?
This is a 4x4 matrix containing all values from 1 to 16 such that the sum of any row, the sum of any column, and the sum of either diagonal, are all the same.
What is [[7, 12, 1, 14], [2, 13, 8, 11], [16, 3, 10, 5], [9, 6, 15, 4]]?