Codeforces Round 650 (Div. 3)

7 problems from Codeforces Round 650 (Div. 3) (contest 1367), difficulty 800-2400. 4/7 solutions verified against sample I/O.

7 items

Codeforces Round 650 (Div. 3)

Div. 3 | 7 problems | 4/7 verified | Difficulty 800-2400 | 23m 6s

#	Problem	Rating	Tags	Accepted	Time	✓
A	Short Substrings	800	implementation, strings	67,694	1m 59s	✓
B	Even Array	800	greedy, math	63,923	3m 58s	✓
C	Social Distance	1300	constructive-algorithms, greedy, math	25,103	3m 5s
D	Task On The Board	1800	constructive-algorithms, greedy, implementation	8,788	6m 59s
E	Necklace Assembly	1900	brute-force, dfs-and-similar, dp	5,826	1m 8s	✓
F1	Flying Sort (Easy Version)	2100	dp, greedy, two-pointers	3,624	1m 50s	✓
F2	Flying Sort (Hard Version)	2400	binary-search, data-structures, dp	1,868	4m 7s

Practice › Codeforces Solutions › Codeforces Round 650 (Div. 3) ›

CF 1367E - Necklace Assembly

We are given a multiset of colored beads, where each bead is just a lowercase letter. From these beads, we want to choose some subset and arrange it in a circle, forming a necklace. The arrangement is circular, so rotations matter but there is no fixed starting point.

Practice › Codeforces Solutions › Codeforces Round 650 (Div. 3) ›

CF 1367F2 - Flying Sort (Hard Version)

We are given a sequence of numbers and a very specific way to reorder it. In one operation, we pick any element and either push it all the way to the front or all the way to the back of the array.

Practice › Codeforces Solutions › Codeforces Round 650 (Div. 3) ›

CF 1367D - Task On The Board

We are given a multiset of lowercase letters, initially written as a string $s$. From this multiset, some letters are discarded and the remaining letters are rearranged arbitrarily to form a new string $t$.

Practice › Codeforces Solutions › Codeforces Round 650 (Div. 3) ›

CF 1367B - Even Array

We are given an array where each position has a fixed “required parity”: even indices must contain even numbers, and odd indices must contain odd numbers.

Practice › Codeforces Solutions › Codeforces Round 650 (Div. 3) ›

CF 1367F1 - Flying Sort (Easy Version)

We are given an array of distinct integers, and our task is to sort it in non-decreasing order using two kinds of operations: moving any element to the front of the array or moving any element to the back.

Practice › Codeforces Solutions › Codeforces Round 650 (Div. 3) ›

CF 1367C - Social Distance

The solution does not correctly address the statement being proved, and it does not provide a valid argument that the pseudo-remainder must be divisible by the leading coefficient $l(v)$.

Practice › Codeforces Solutions › Codeforces Round 650 (Div. 3) ›

CF 1367A - Short Substrings

The problem gives you a string b that is formed by taking every consecutive pair of characters from some secret string a and concatenating them. Your goal is to reconstruct the original string a.