Dijkstra's algorithm for finding the shortest path from a start node to all other nodes in a graph.

Given an adjacency matrix representation of the graph and the node to start the algorithm from, find the shortest path from a start node to all other nodes in the graph.

Input: adjacency_matrix =[ [0, 4, 0, 0], [4, 0, 12, 0], [0, 12, 0, 0], [0, 0, 0, 0] ] Output: { "start_node": 3, "parent_list": [None, None, None, None], "shortest_distances": [float('inf'), float('inf'), float('inf'), 0] }

The unit tests provided don't cover all test cases needed to verify correctness.