Problem

Source: 2016 Argentina L2 P6

Tags: combinatorics



There are $999$ black points marked on a circle, dividing it into $999$ arcs of length $1$. We need to place $d$ arcs of lengths $1, 2, \dots, d$ such that each arc starts and ends at two black points, and none of the $d$ arcs is contained within another. Find the maximum value of $d$ for which this construction is possible. Note: Two arcs can have one or more black points in common.