Codeforces Round 1020 (Div. 3)

8 problems from Codeforces Round 1020 (Div. 3) (contest 2106), difficulty 800-2500. 2/8 solutions verified against sample I/O.

8 items

Codeforces Round 1020 (Div. 3)

Div. 3 | 8 problems | 2/8 verified | Difficulty 800-2500 | 13m 16s

#	Problem	Rating	Tags	Accepted	Time	✓
A	Dr. TC	800	brute-force, math	36,352	1m 20s	✓
B	St. Chroma	900	constructive-algorithms, greedy, math	28,376	1m 27s
C	Cherry Bomb	1000	greedy, math, sortings	25,596	1m 12s	✓
D	Flower Boy	1500	binary-search, dp, greedy	12,261	1m 32s
E	Wolf	1800	binary-search, greedy, math	5,932	1m 45s
F	Goblin	1900	dfs-and-similar, dp, dsu	4,418	2m 41s
G1	Baudelaire (easy version)	2200	binary-search, constructive-algorithms, divide-and-conquer	1,612	1m 41s
G2	Baudelaire (hard version)	2500	binary-search, dfs-and-similar, divide-and-conquer	609	1m 38s

Practice › Codeforces Solutions › Codeforces Round 1020 (Div. 3) ›

CF 2106G2 - Baudelaire (hard version)

We are given a tree with up to 1000 nodes, and each node hides a value of either 1 or −1. The tree is rooted somewhere, but the root is unknown to us.

Practice › Codeforces Solutions › Codeforces Round 1020 (Div. 3) ›

CF 2106G1 - Baudelaire (easy version)

We are given a tree of size $n$, where each node carries a value of either $1$ or $-1$. The tree is connected in such a way that every node is adjacent to node $1$.

Practice › Codeforces Solutions › Codeforces Round 1020 (Div. 3) ›

CF 2106F - Goblin

We are asked to find the largest connected set of zeros in an $n times n$ grid that is built from a single binary string $s$. Each row of the grid is generated by flipping one character of $s$ at the row's index.

Practice › Codeforces Solutions › Codeforces Round 1020 (Div. 3) ›

CF 2106E - Wolf

We are given a permutation of numbers from 1 to n, and we need to answer many independent queries. Each query picks a subarray range $[l, r]$ and a target value $k$. We imagine performing the standard binary search process on that fixed range, even though the array is not sorted.

Practice › Codeforces Solutions › Codeforces Round 1020 (Div. 3) ›

CF 2106D - Flower Boy

We are given a sequence of flowers in a row, each with a numeric beauty value. Igor wants to collect a fixed number of flowers, exactly $m$, moving strictly left to right.

Practice › Codeforces Solutions › Codeforces Round 1020 (Div. 3) ›

CF 2106B - St. Chroma

We are given a list that must be a permutation of numbers from 0 to n−1. As we reveal this permutation from left to right, we compute a running value: after each prefix, we take the smallest non-negative integer that is missing from that prefix.

Practice › Codeforces Solutions › Codeforces Round 1020 (Div. 3) ›

CF 2106A - Dr. TC

We are given a binary string s of length n, and we imagine creating n new strings by flipping exactly one bit of s in each position. The resulting strings are arranged as rows of an n × n board. Our goal is to count the total number of 1s on this board.

Practice › Codeforces Solutions › Codeforces Round 1020 (Div. 3) ›

CF 2106C - Cherry Bomb

We are given two arrays of length $n$, $a$ and $b$. Array $a$ is fully known, and $b$ has some missing elements marked as $-1$. The goal is to fill in the missing elements in $b$ such that the sum $ai + bi$ is constant for all $i$. Each element in $b$ must remain within $[0, k]$.