Sort a linked list using insertion sort.
We have explained Insertion Sort at Slide 7 of Arrays
Insertion Sort Wiki has some details on Insertion Sort as well.
Input : 1 -> 3 -> 2 Return 1 -> 2 -> 3
NOTE: You only need to implement the given function. Do not read input, instead use the arguments to the function. Do not print the output, instead return values as specified. Still have a doubt? Checkout Sample Codes for more details.