Codeforces Round 803 (Div. 2)

Solutions for Codeforces Round 803 (Div. 2) (contest 1698). 3/7 problems verified against sample I/O. Difficulty range: 800-2900.

7 items

Codeforces Round 803 (Div. 2)

Type: Div. 2 | Problems: 7 | Verified: 3/7 | Rating range: 800-2900 | Time: 21m 25s

Problem	Name	Rating	Tags	Solve Time	Verified
A	XOR Mixup	800	bitmasks, brute-force	2m 49s	✗
B	Rising Sand	800	constructive-algorithms, greedy, implementation	1m 47s	✓
C	3SUM Closure	1300	brute-force, data-structures	7m 35s	✓
D	Fixed Point Guessing	1600	binary-search, constructive-algorithms, interactive	2m 13s	✗
E	PermutationForces II	2300	brute-force, combinatorics, greedy	2m 23s	✗
F	Equal Reversal	2800	constructive-algorithms, graphs, implementation	2m 26s	✗
G	Long Binary String	2900	bitmasks, math, matrices	2m 12s	✓

Practice › Codeforces Solutions › Codeforces Round 803 (Div. 2) ›

CF 1698C - 3SUM Closure

We are asked to determine if an array of integers is 3SUM-closed, which means that for every triple of distinct elements in the array, the sum of those three elements is itself present somewhere in the array.

Practice › Codeforces Solutions › Codeforces Round 803 (Div. 2) ›

CF 1698G - Long Binary String

We are given a small binary string s of length up to 35, and we need to manipulate a conceptual binary string t of length $10^{100}$, which is initially all zeros. The operation allowed is selecting a contiguous substring of t of the same length as s and XOR-ing it with s.

Practice › Codeforces Solutions › Codeforces Round 803 (Div. 2) ›

CF 1698F - Equal Reversal

We are given two arrays, a and b, each of length n. The array b is a permutation of a, so they contain the same multiset of values but possibly in a different order.

Practice › Codeforces Solutions › Codeforces Round 803 (Div. 2) ›

CF 1698E - PermutationForces II

We start with a permutation a, which represents the initial ordering of 1..n. Over n steps, we are allowed to repeatedly swap elements, but the swap range grows in a constrained way: at step i, we can only operate on positions from i to min(i+s, n).

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CF 1698D - Fixed Point Guessing

We start with a permutation of numbers from 1 to n, but the permutation is not arbitrary. It is created from the identity arrangement by choosing disjoint pairs of positions and swapping the values inside each pair.

Practice › Codeforces Solutions › Codeforces Round 803 (Div. 2) ›

CF 1698A - XOR Mixup

We are given an array of length n that was generated by taking an original array of length n-1, computing the XOR of all its elements, appending that XOR to the array, and then shuffling the result.

Practice › Codeforces Solutions › Codeforces Round 803 (Div. 2) ›

CF 1698B - Rising Sand

We are given a row of sand piles, each with some initial height. We are allowed to perform an operation that picks a contiguous segment of fixed length k and increases every pile in that segment by one unit. We can repeat this operation any number of times and on any segments.