Last active
February 20, 2019 06:18
-
-
Save yasufumy/e6477c836baa85735f6019bc0b0c1460 to your computer and use it in GitHub Desktop.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| INF = float('inf') | |
| def dag_shortest_path(graph, weights, torder, s): | |
| d = {v: INF for v in graph} | |
| d[s] = 0 | |
| pi = {s: None} | |
| for u in torder: | |
| for v in graph[u]: | |
| d_temp = d[u] + weights[u, v] | |
| if d_temp < d[v]: | |
| d[v] = d_temp | |
| pi[v] = u | |
| return d, pi | |
| if __name__ == '__main__': | |
| graph = {'A': ['B', 'C'], | |
| 'B': ['C', 'D'], | |
| 'C': ['D', 'E', 'F'], | |
| 'D': ['E', 'F'], | |
| 'E': ['F'], | |
| 'F': []} | |
| weights = {('A', 'B'): 5, ('A', 'C'): 2, | |
| ('B', 'C'): 2, ('B', 'D'): 6, | |
| ('C', 'D'): 7, ('C', 'E'): 4, ('C', 'F'): 2, | |
| ('D', 'E'): -1, ('D', 'F'): 1, | |
| ('E', 'F'): -2} | |
| torder = ['A', 'B', 'C', 'D', 'E', 'F'] | |
| print(dag_shortest_path(graph, weights, torder, 'B')) |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment