Replay of BUET IUPC 2026, Powered By Phitron

12 problems from Replay of BUET IUPC 2026, Powered By Phitron (contest 106356), difficulty -. 12/12 solutions verified against sample I/O.

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Replay of BUET IUPC 2026, Powered By Phitron

Special | 12 problems | 12/12 verified | Difficulty - | 11m 53s

# Problem Rating Tags Accepted Time ✓
A Quantum Corridor 52s ✓
B Easy Composite 52s ✓
C Path of Crows 1m 10s ✓
D Dual Star 1m 14s ✓
E Chorki 42s ✓
F Mandatory XOR Problem 55s ✓
G Genome Evolution 44s ✓
H Pothchola 54s ✓
I Cosmic Bit Flip 1m 9s ✓
J Prefix Reversal 58s ✓
K Lottery 1m 30s ✓
L Sapure 53s ✓
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CF 106356E - Chorki

We are given a binary array and we are allowed to rotate it circularly. After choosing a rotation, we compare the original array with this rotated version element by element using XOR. Wherever the two arrays differ, we get a 1 in the resulting array, otherwise we get a 0.
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CF 106356I - Cosmic Bit Flip

The country can be seen as a tree with $n$ cities connected by $n-1$ roads, meaning there is exactly one simple path between any two cities. Some cities contain a special property, a “ley-line”, and we are only interested in the parity of how many such cities lie on a path.
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CF 106356J - Prefix Reversal

We are given an array of length n. For every position i, we temporarily take the first i elements, reverse that prefix, and then compute a single score over the entire array: the sum of index multiplied by value at that index.
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CF 106356D - Dual Star

We are given two identical spherical planets whose centers move in 3D but are always constrained to lie on a fixed circular orbit.
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CF 106356H - Pothchola

We are given a set of values placed on nodes of a directed graph. Between every ordered pair of distinct nodes $u$ and $v$, we may or may not have a directed edge from $u$ to $v$, and the rule is completely determined by their values $au$ and $av$.
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CF 106356L - Sapure

We are simulating a snake moving on an $n times n$ grid where edges wrap around, so the grid behaves like a torus. The snake starts as a single cell at $(1,1)$.
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CF 106356G - Genome Evolution

We are given a system that generates a sequence of integers, where each integer represents a genome encoded as a bitmask. Each bit indicates whether a particular genetic marker is present. The evolution rule is deterministic. The first two genomes are fixed as $a$ and $b$.
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CF 106356A - Quantum Corridor

We are given a one-dimensional corridor of chambers numbered from 1 to n. A particle starts at a fixed chamber i. From any chamber, it can attempt to move left or right by exactly a steps, or by exactly b steps.
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CF 106356B - Easy Composite

We are given several prime numbers. For each prime $p$, we may place one or more decimal digits in front of its decimal representation. The resulting number is the concatenation of the chosen prefix and $p$.
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CF 106356K - Lottery

There are many people, and each person owns a small number of lottery tickets, at most five per person. A draw repeatedly picks a single ticket uniformly from all remaining tickets.
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CF 106356F - Mandatory XOR Problem

We are asked to consider all ways of distributing a fixed total sum across an array of length $N$, where each element is a non-negative integer and the total sum of all elements is exactly $S$. Every such array is a composition of $S$ into $N$ parts.
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CF 106356C - Path of Crows

We are given a tree with $n$ vertices, meaning $n$ nests connected by $n-1$ undirected branches, with exactly one simple path between any two nests.
codeforces competitive-programming Jun 19, 2026