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MathNet 2015-part-03 — 191 problems (EN–VI) Question 174

Math Olympiad Vault · MathNet 2015-part-03 — 191 problems (EN–VI)

Question 174

There are $n$ students standing in line in positions $1$ to $n$. While the teacher looks away, some students change their positions. When the teacher looks back, they are standing in line again. If a student who was initially in position $i$ is now in position $j$, we say the student moved for $|i-j|$ steps. Determine the maximal sum of steps of all students that they can achieve.