Art of Problem Solving
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2023 IMO Problems/Problem 5: Difference between revisions

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==Solution==
==Solution==
k=<math>\floor(\log(n))+1</math>
<math>k=1</math>
https://www.youtube.com/watch?v=jZNIpapyGJQ [Video contains solutions to all day 2 problems]
https://www.youtube.com/watch?v=jZNIpapyGJQ [Video contains solutions to all day 2 problems]



Revision as of 16:35, 30 April 2024

Problem

Let $n$ be a positive integer. A Japanese triangle consists of $1 + 2 + \dots + n$ circles arranged in an equilateral triangular shape such that for each $i = 1$, $2$, $\dots$, $n$, the $i^{th}$ row contains exactly $i$ circles, exactly one of which is coloured red. A ninja path in a Japanese triangle is a sequence of $n$ circles obtained by starting in the top row, then repeatedly going from a circle to one of the two circles immediately below it and finishing in the bottom row. Here is an example of a Japanese triangle with $n = 6$, along with a ninja path in that triangle containing two red circles.

[Image to be inserted; also available in solution video]

Solution

$k=1$ https://www.youtube.com/watch?v=jZNIpapyGJQ [Video contains solutions to all day 2 problems]

See Also

2023 IMO (Problems) • Resources
Preceded by
Problem 4
1 2 3 4 5 6 Followed by
Problem 6
All IMO Problems and Solutions