Problem - Minimum Number of Arrows

Balloons are represented as intervals on the x-axis. An arrow shot at position $x$ bursts all balloons where $x_{start} \leq x \leq x_{end}$.

Find the minimum number of arrows to burst all balloons. For balloons $[[10,16],[2,8],[1,6],[7,12]]$, answer is $2$. One arrow at $x=6$ bursts $[2,8]$ and $[1,6]$.

Another at $x=11$ bursts $[10,16]$ and $[7,12]$. Tricky: overlapping balloons can be burst by the same arrow. Sorting by end point ensures you process balloons in optimal order.