quick sort algorithm

shortest path in graph

correction on doubly linked list

reverse the linkedlist

implement method delete node by given key

major changes on insertAfterThat func

Implement method insert at front, end and the given after position

some info added

insert node in linkedlist

doubly linkedlist implementation

singly linkedlist complete revision done

Implement method delete first node , last node , and the given key node (revision)

printlist , search data exist and insert After given position methos implement

linkedlist implementation , insert at front and the end method introduced

modification edge case