README.md

Priority-Queues

Implementation of Johnson's APSP algorithm using 4 different priority queues and a comparision of their relative performance.

Steps to run

Compile the program by-

g++ main.cpp

Execute

./a.out 1 # for simple array-based heap execution  

./a.out 2 # for binary heap based execution

./a.out 3 # For binomial heap based execution

./a.out 4 # For fibonacci heap based execution

If no argument is supplied, fibonacci heap based Johnson algorithm will be executed by default.

Input format

First line of the input will specify the number of test cases.
For each test case, supply two integers N and D in the first line, specifying the number of vertices N, and D=0 for an undirected graph and D=1 for a directed graph. The next N lines of the test case should contain the NxN adjacency matrix of the graph, with each element specifying the edge weight (-999<W<999). If an edge does not exit between two vertices, enter the edge weight as '999999'.

Output format

For each test case,

1. -1 is printed if a negative cycle exists in the graph.
2. Else, N lines are printed, in which the k^th entry in the i^th line tells the lenght of the shortest path to the k^th vertex from the i^th vertex.

The last line of the output contains the time taken for each of the testcases to complete, with the k^th entry corresponding to the k^th testcase.