Codeforces Round 682 (Div. 2)

Solutions for Codeforces Round 682 (Div. 2) (contest 1438). 1/6 problems verified against sample I/O. Difficulty range: 800-3000.

6 items

Codeforces Round 682 (Div. 2)

Type: Div. 2 | Problems: 6 | Verified: 1/6 | Rating range: 800-3000 | Time: 16m 19s

Problem Name Rating Tags Solve Time Verified
A Specific Tastes of Andre 800 constructive-algorithms, implementation 1m 35s ✗
B Valerii Against Everyone 1000 constructive-algorithms, data-structures, greedy 6m 10s ✓
C Engineer Artem 2000 2-sat, chinese-remainder-theorem, constructive-algorithms 2m 39s ✗
D Powerful Ksenia 2200 bitmasks, constructive-algorithms, math 1m 33s ✗
E Yurii Can Do Everything 2500 binary-search, bitmasks, brute-force 2m 46s ✗
F Olha and Igor 3000 interactive, probabilities, trees 1m 36s ✗
Practice › Codeforces Solutions › Codeforces Round 682 (Div. 2) ›

CF 1438B - Valerii Against Everyone

Ah, now I see exactly what is happening. The ValueError: not enough values to unpack occurs because the previous parsing assumed that every test case’s first line has exactly three numbers (n, k, m).
codeforces competitive-programming constructive-algorithms data-structures greedy sortings Jun 11, 2026
Practice › Codeforces Solutions › Codeforces Round 682 (Div. 2) ›

CF 1438E - Yurii Can Do Everything

The key issue is that this is a constructive problem. The output shown in the statement is only one valid sequence of operations, not the unique correct output. Your program's output is different from the sample output, but that does not mean it is wrong.
codeforces competitive-programming binary-search bitmasks brute-force constructive-algorithms divide-and-conquer two-pointers Jun 11, 2026
Practice › Codeforces Solutions › Codeforces Round 682 (Div. 2) ›

CF 1438F - Olha and Igor

We are given a perfect binary tree of height $h$, which contains $n = 2^h - 1$ nodes. Each node has a unique label from 1 to $n$, but the labeling is completely unknown. Our task is to determine the label of the root.
codeforces competitive-programming interactive probabilities trees Jun 11, 2026
Practice › Codeforces Solutions › Codeforces Round 682 (Div. 2) ›

CF 1438D - Powerful Ksenia

We are given a sequence of positive integers, and we are allowed to perform a very specific transformation: pick three distinct positions and replace all three values by their bitwise XOR.
codeforces competitive-programming bitmasks constructive-algorithms math Jun 11, 2026
Practice › Codeforces Solutions › Codeforces Round 682 (Div. 2) ›

CF 1438C - Engineer Artem

The key issue is that this is a constructive problem. The output shown in the statement is only one valid sequence of operations, not the unique correct output. Your program's output is different from the sample output, but that does not mean it is wrong.
codeforces competitive-programming 2-sat chinese-remainder-theorem constructive-algorithms fft flows Jun 11, 2026
Practice › Codeforces Solutions › Codeforces Round 682 (Div. 2) ›

CF 1438A - Specific Tastes of Andre

The problem asks us to construct arrays with a very strict divisibility property. For an array to be called perfect, every subarray, regardless of length or position, must have a sum divisible by its length.
codeforces competitive-programming constructive-algorithms implementation Jun 11, 2026