Codeforces Round 1079 (Div. 2)

Solutions for Codeforces Round 1079 (Div. 2) (contest 2197). 3/7 problems verified against sample I/O. Difficulty range: 800-2500.

7 items

Codeforces Round 1079 (Div. 2)

Type: Div. 2 | Problems: 7 | Verified: 3/7 | Rating range: 800-2500 | Time: 11m 24s

Problem	Name	Rating	Tags	Solve Time	Verified
A	Friendly Numbers	800	binary-search, brute-force, expression-parsing	1m 6s	✓
B	Array and Permutation	1100	implementation, schedules, sortings	1m 21s	✓
C	Game with a Fraction	1200	games, greedy, math	2m 10s	✗
D	Another Problem about Beautiful Pairs	1600	brute-force, data-structures, divide-and-conquer	1m 47s	✓
E1	Interactive Graph (Simple Version)	1800	binary-search, combinatorics, dfs-and-similar	1m 27s	✗
E2	Interactive Graph (Hard Version)	2000	combinatorics, dfs-and-similar, dp	1m 28s	✗
F	Double Bracket Sequence	2500	data-structures, dp, flows	2m 5s	✗

Practice › Codeforces Solutions › Codeforces Round 1079 (Div. 2) ›

CF 2197F - Double Bracket Sequence

The value $V = 7frac{1}{16}$ corresponds to the chi-square statistic computed from $k = 11$ categories, as in Eq. (5). The number of degrees of freedom is therefore $nu = k - 1 = 10$.

Practice › Codeforces Solutions › Codeforces Round 1079 (Div. 2) ›

CF 2197E2 - Interactive Graph (Hard Version)

We are tasked with reconstructing a hidden directed acyclic graph with n vertices by asking queries about its paths. Each query gives the k-th path in lexicographical order.

Practice › Codeforces Solutions › Codeforces Round 1079 (Div. 2) ›

CF 2197E1 - Interactive Graph (Simple Version)

We are tasked with reconstructing an unknown directed acyclic graph using an interactive interface. The graph has n vertices and an unknown number of edges m, and no loops or multiple edges.

Practice › Codeforces Solutions › Codeforces Round 1079 (Div. 2) ›

CF 2197C - Game with a Fraction

The value $V = 7frac{1}{16}$ corresponds to the chi-square statistic computed from $k = 11$ categories, as in Eq. (5). The number of degrees of freedom is therefore $nu = k - 1 = 10$.

Practice › Codeforces Solutions › Codeforces Round 1079 (Div. 2) ›

CF 2197D - Another Problem about Beautiful Pairs

We are given an array of integers, and we need to count pairs of indices (i, j) where i < j and the product of the corresponding values equals the distance between the indices: a[i] a[j] = j - i.

Practice › Codeforces Solutions › Codeforces Round 1079 (Div. 2) ›

CF 2197B - Array and Permutation

We are given a permutation p of length n and an array a of the same length. A permutation is an array of distinct integers from 1 to n, in some order.

Practice › Codeforces Solutions › Codeforces Round 1079 (Div. 2) ›

CF 2197A - Friendly Numbers

We are given an integer $x$, and we want to count how many integers $y$ satisfy a very specific balancing condition: if you take $y$ and subtract the sum of its digits, you land exactly on $x$.