Codeforces LATOKEN Round 1 (Div. 1 + Div. 2)

Solutions for Codeforces LATOKEN Round 1 (Div. 1 + Div. 2) (contest 1534). 2/9 problems verified against sample I/O. Difficulty range: 800-3500.

9 items

Codeforces LATOKEN Round 1 (Div. 1 + Div. 2)

Type: Div. 1+2 | Problems: 9 | Verified: 2/9 | Rating range: 800-3500 | Time: 38m 20s

Problem Name Rating Tags Solve Time Verified
A Colour the Flag 800 brute-force, implementation 1m 25s ✗
B Histogram Ugliness 1100 greedy, implementation, math 8m 55s ✓
C Little Alawn's Puzzle 1300 combinatorics, dp, dsu 1m 46s ✓
D Lost Tree 1800 constructive-algorithms, interactive, trees 6m 14s ✗
E Lost Array 2300 graphs, greedy, interactive 2m 40s ✗
F1 Falling Sand (Easy Version) 2500 dfs-and-similar, graphs, greedy 2m 51s ✗
F2 Falling Sand (Hard Version) 3000 dfs-and-similar, dp, graphs 2m 41s ✗
G A New Beginning 3300 data-structures, dp, geometry 10m 16s ✗
H Lost Nodes 3500 constructive-algorithms, dp, graphs 1m 32s ✗
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CF 1534G - A New Beginning

The claimed output 10 for "0?10" is actually impossible. There are only 10 total substrings of a length-4 string, and two of them are not beautiful: - "0?10" cannot be made alternating. - "?10" cannot be made alternating. So the correct answer is 8.
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CF 1534H - Lost Nodes

Consider a closed container of fixed volume $V$ containing an ideal gas whose bulk temperature is $T1$. The container walls are maintained at temperature $T$, and $T$ need not equal $T1$.
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CF 1534F2 - Falling Sand (Hard Version)

We are given a grid representing a vertical board filled with sand blocks. Each cell either contains a block or is empty. There are also target requirements per column: for every column, we want at least a certain number of sand blocks to end up in a counter at the bottom.
codeforces competitive-programming dfs-and-similar dp graphs greedy Jun 10, 2026
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CF 1534B - Histogram Ugliness

We are given a histogram represented as an array of integers, where each integer is the height of a vertical bar. Little Dormi can decrease the height of any bar by one repeatedly, and each such decrease counts as an operation.
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CF 1534D - Lost Tree

We are asked to reconstruct an unweighted tree given a limited interactive query mechanism. The tree has $n$ nodes labeled $1$ through $n$, and we are allowed to query the distance from any chosen node to all others.
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CF 1534F1 - Falling Sand (Easy Version)

We are given a grid of n rows and m columns where each cell either contains a sand block () or is empty (.). Alongside the grid, we are given an array a of length m. In this easy version of the problem, each a[i] exactly equals the number of sand blocks in column i.
codeforces competitive-programming dfs-and-similar graphs greedy Jun 10, 2026
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CF 1534E - Lost Array

We are given a hidden array of length n. We cannot see its elements directly, but we are allowed to ask queries. Each query chooses exactly k distinct positions, and the system returns the XOR of the values at those positions.
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CF 1534C - Little Alawn's Puzzle

We are given a 2 by n grid where each row is a permutation of numbers from 1 to n. So every number appears exactly once in each row, and every column contains two distinct values. The only operation allowed is swapping the two values inside any column.
codeforces competitive-programming combinatorics dp dsu graphs math Jun 10, 2026
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CF 1534A - Colour the Flag

The claimed output 10 for "0?10" is actually impossible. There are only 10 total substrings of a length-4 string, and two of them are not beautiful: - "0?10" cannot be made alternating. - "?10" cannot be made alternating. So the correct answer is 8.
codeforces competitive-programming brute-force implementation Jun 10, 2026