The 2025 ICPC Japan Online First Round Contest

9 problems from The 2025 ICPC Japan Online First Round Contest (contest 106185), difficulty -. 9/9 solutions verified against sample I/O.

9 items

The 2025 ICPC Japan Online First Round Contest

ICPC/IOI | 9 problems | 9/9 verified | Difficulty - | 8m 10s

#	Problem	Time	✓
A	2025	42s	✓
B	Prefix and Suffix Can Be the Same	45s	✓
C	Calendar of an Enthusiastic Worker	51s	✓
D	Ancient Game Board	51s	✓
E	To Be Discontinued	1m 1s	✓
F	Dog Tricks	55s	✓
G	Number of Faces	59s	✓
H	Parentheses	59s	✓
I	Preparing the Lunch	1m 7s	✓

Practice › Codeforces Solutions › The 2025 ICPC Japan Online First Round Contest ›

CF 106185G - Number of Faces

We are given two convex polygons, each lying on a separate horizontal plane, one at height $z = 1$ and the other at $z = 2$. What is fixed is not their coordinates, but only the sequence of interior angles for each polygon in cyclic order.

Practice › Codeforces Solutions › The 2025 ICPC Japan Online First Round Contest ›

CF 106185A - 2025

We are given a sequence of test cases. Each test case contains a single integer $n$, and for each one we conceptually build an $n times n$ multiplication table where the cell in row $a$ and column $b$ contains the product $a cdot b$.

Practice › Codeforces Solutions › The 2025 ICPC Japan Online First Round Contest ›

CF 106185H - Parentheses

We are given a row of positions, each position holding a stamp labeled with either an opening or closing parenthesis. We do not take substrings in the usual sense. Instead, we build a sequence by walking along these positions.

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CF 106185D - Ancient Game Board

We are given a rectangular grid made of two colors, represented by . and . This grid is not arbitrary; it is assumed to be a fragment of a much larger infinite tiling. The hypothesized structure is a chessboard-like arrangement of identical square blocks.

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CF 106185I - Preparing the Lunch

We are given a circle of $2n$ seats. Each seat initially holds a labeled item, and labels repeat, with the guarantee that every label appears an even number of times. The seats are arranged so that each position $i$ has a unique opposite position $i+n$ on the circle.

Practice › Codeforces Solutions › The 2025 ICPC Japan Online First Round Contest ›

CF 106185E - To Be Discontinued

We are given a tree of $n$ planets. Each planet is connected to its parent by exactly one bidirectional space route, and each route has a deadline. The route can be used only if, at the moment you start traversing it, your current time is not greater than its deadline.

Practice › Codeforces Solutions › The 2025 ICPC Japan Online First Round Contest ›

CF 106185F - Dog Tricks

We are given a line of plates, each holding either an apple (a) or a banana (b). We start from an initial configuration and want to transform it into a target configuration using a sequence of operations, but the operations are not arbitrary single swaps.

Practice › Codeforces Solutions › The 2025 ICPC Japan Online First Round Contest ›

CF 106185C - Calendar of an Enthusiastic Worker

We are given a timeline starting from today, where today is fixed as Monday. The calendar then proceeds day by day, and we want to count how many of the next m days are working days. Two types of restrictions define non-working days.

Practice › Codeforces Solutions › The 2025 ICPC Japan Online First Round Contest ›

CF 106185B - Prefix and Suffix Can Be the Same

We are given a string $s$. The task is to construct a different string $t$ such that two conditions hold simultaneously: the beginning of $t$ matches the entire string $s$, and the end of $t$ also matches the entire string $s$.