The following is the Recurrence relation formula for Merge Sort. Use this to find the time complexity.

$1.$ T$($n$)=2$T$($n$/2)+$ O$($n$)$

$2.$ T$($n$)$: Time required to sort an array of size n$.$

$3.$ T$($n$/2)$: Time required to sort two half arrays.

$4.$ O$($n$)$: Time taken to merge sorted arrays of $2.$