Codeforces Round 880 (Div. 1)

Solutions for Codeforces Round 880 (Div. 1) (contest 1835). 1/6 problems verified against sample I/O. Difficulty range: 1700-3500.

6 items

Codeforces Round 880 (Div. 1)

Type: Div. 1 | Problems: 6 | Verified: 1/6 | Rating range: 1700-3500 | Time: 8m 46s

Problem Name Rating Tags Solve Time Verified
A k-th equality 1700 brute-force, implementation, math 1m 11s ✓
B Lottery 2500 binary-search, brute-force, greedy 2m 3s ✗
C Twin Clusters 2600 bitmasks, brute-force, constructive-algorithms 1m 26s ✗
D Doctor's Brown Hypothesis 2900 dfs-and-similar, graphs, math 1m 27s ✗
E Old Mobile 3500 combinatorics, dp, probabilities 1m 35s ✗
F Good Graph 3500 bitmasks, dfs-and-similar, graph-matchings 1m 4s ✗
Practice › Codeforces Solutions › Codeforces Round 880 (Div. 1) ›

CF 1835F - Good Graph

Investigate the "improved" KS test suggested in the answer to exercise 6. Let $X1, X2, ldots, Xn$ be independent observations drawn from a continuous distribution function $F(x)$.
codeforces competitive-programming bitmasks dfs-and-similar graph-matchings graphs implementation Jun 9, 2026
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CF 1835E - Old Mobile

We are asked to compute the expected number of button presses needed to type a number on an old mobile device with an unfamiliar keyboard. The keyboard has $m$ digit buttons and a backspace. Jan, the user, cannot distinguish which button is which until he presses it.
codeforces competitive-programming combinatorics dp probabilities Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 880 (Div. 1) ›

CF 1835D - Doctor's Brown Hypothesis

We have a directed graph representing planets connected by wormholes. Each planet has exactly one battleship. The rebels want to pick either a single ship or a pair of ships that can move for exactly k hours along wormholes.
codeforces competitive-programming dfs-and-similar graphs math number-theory Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 880 (Div. 1) ›

CF 1835B - Lottery

The proposed solution directly addresses the exercise by analyzing the asymptotic behavior of the finite-$n$ Kolmogorov-Smirnov distribution.
codeforces competitive-programming binary-search brute-force greedy math two-pointers Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 880 (Div. 1) ›

CF 1835C - Twin Clusters

We are given a sequence of galaxies, each with a certain number of stars. The total number of galaxies in a test case is always a power of two, specifically $2^{k+1}$. Each galaxy has a star count between 0 and $4^k - 1$.
codeforces competitive-programming bitmasks brute-force constructive-algorithms math probabilities Jun 9, 2026
Practice › Codeforces Solutions › Codeforces Round 880 (Div. 1) ›

CF 1835A - k-th equality

We are asked to enumerate all equalities of the form a + b = c where a, b, and c are positive integers with exactly A, B, and C digits respectively.
codeforces competitive-programming brute-force implementation math Jun 9, 2026