Difference between revisions of "2017 IMO Problems/Problem 5"

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==Problem==
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An integer <math>N \ge 2</math> is given. A collection of <math>N(N + 1)</math> soccer players, no two of whom are of the same height, stand in a row. Sir Alex wants to remove <math>N(N - 1)</math> players from this row leaving a new row of <math>2N</math> players in which the following <math>N</math> conditions hold:
 
An integer <math>N \ge 2</math> is given. A collection of <math>N(N + 1)</math> soccer players, no two of whom are of the same height, stand in a row. Sir Alex wants to remove <math>N(N - 1)</math> players from this row leaving a new row of <math>2N</math> players in which the following <math>N</math> conditions hold:
  
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==Solution==
 
==Solution==
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{{solution}}
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==See Also==
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{{IMO box|year=2017|num-b=4|num-a=6}}

Latest revision as of 00:42, 19 November 2023

Problem

An integer $N \ge 2$ is given. A collection of $N(N + 1)$ soccer players, no two of whom are of the same height, stand in a row. Sir Alex wants to remove $N(N - 1)$ players from this row leaving a new row of $2N$ players in which the following $N$ conditions hold:

($1$) no one stands between the two tallest players,

($2$) no one stands between the third and fourth tallest players,

$\;\;\vdots$

($N$) no one stands between the two shortest players.

Show that this is always possible.

Solution

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See Also

2017 IMO (Problems) • Resources
Preceded by
Problem 4
1 2 3 4 5 6 Followed by
Problem 6
All IMO Problems and Solutions