Due to change in PriorityQueue method name - updating deleteElement to
deleteTopElement
Adding DisjointSet data structure. This is used in Dijkstra's algorithm.
Implemented both union by rank and path compression heuristics.
Adding Minimum Spanning Tree and Dijkstra's algorithm.
Adding Rank, Parent and a Comparator based on Rank - used in Prims and
Dijkstras algorithm.
Adding isEmpty, deleteElement and deleteElementAt functions.
Seperating out dfsList and bfsList
Due to change in PriorityQueue - deleteElement is now renamed to be
deleteTopElement