Merge nodes Given an array of nums where nums$[$i$]=[$xi$,$ yi$),$ unify all connecting numbers, and return an array of the non$-$connecting numbers that cross all the numbers in the given input. Example $1$: Input: nums$=[[2,6],[8,10],[1,3],[15,18]]$ Output: $[[1,6],[8,10],[15,18]]$ Explanation: Since points $[1,3]$ and $[2\mathrm{.}6)$ cross, unify them into $[1,6].$ Example $2$: Input: nums $=[[1\mathrm{.}4],[4,5]]$ Output: $[[1\mathrm{.}5]]$ Explanation: nums $[1,4]$ and $[4,5]$ are considered crossing. Constraints: $1<=$ nums.length $<=104$ nums$[$i$].$length $==20<=$ xi $<=$ yi $<=104$