Non-overlapping - Walkthrough

Intervals: [[1,2], [2,3], [3,4], [1,3]]. Sorted by end: [[1,2], [2,3], [1,3], [3,4]]. $1.$ Select [1,2]. Last end = $2$.

$2.$ [2,3]: start $2$ >= $2$. Select! Last end = $3$.

$3.$ [1,3]: start $1$ < $3$. Conflicts. Skip.

$4.$ [3,4]: start $3$ >= $3$. Select! Last end = $4$. Max non-overlapping: $3$. Total intervals: $4$. Minimum removals: $4$ - $3$ = $1$. The removed interval is [1,3]. Notice touching intervals like [2,3] and [3,4] are allowed. The overlap check is start >= lastEnd.