From 6c497c692b53da154458e82d719cc9c25268e132 Mon Sep 17 00:00:00 2001 From: swjtuhjf Date: Tue, 12 Nov 2024 14:04:38 +0800 Subject: [PATCH] =?UTF-8?q?=E6=B7=BB=E5=8A=A0=200096.=E5=9F=8E=E5=B8=82?= =?UTF-8?q?=E9=97=B4=E8=B4=A7=E7=89=A9=E8=BF=90=E8=BE=93III=20python3=20SP?= =?UTF-8?q?FA=E7=89=88=E6=9C=AC?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- .../0096.城市间货物运输III.md | 45 +++++++++++++++++++ 1 file changed, 45 insertions(+) diff --git a/problems/kamacoder/0096.城市间货物运输III.md b/problems/kamacoder/0096.城市间货物运输III.md index a41332cf..109027b1 100644 --- a/problems/kamacoder/0096.城市间货物运输III.md +++ b/problems/kamacoder/0096.城市间货物运输III.md @@ -703,6 +703,9 @@ public class Main { ``` ### Python + +Bellman-Ford方法求解单源有限最短路 + ```python def main(): # 輸入 @@ -736,6 +739,48 @@ def main(): +if __name__ == "__main__": + main() +``` + +SPFA方法求解单源有限最短路 + +```python +from collections import deque +from math import inf + + +def main(): + n, m = [int(i) for i in input().split()] + graph = [[] for _ in range(n+1)] + for _ in range(m): + v1, v2, val = [int(i) for i in input().split()] + graph[v1].append([v2, val]) + src, dst, k = [int(i) for i in input().split()] + min_dist = [inf for _ in range(n+1)] + min_dist[src] = 0 # 初始化起点的距离 + que = deque([src]) + + while k != -1 and que: + visited = [False for _ in range(n+1)] # 用于保证每次松弛时一个节点最多加入队列一次 + que_size = len(que) + temp_dist = min_dist.copy() # 用于记录上一次遍历的结果 + for _ in range(que_size): + cur_node = que.popleft() + for next_node, val in graph[cur_node]: + if min_dist[next_node] > temp_dist[cur_node] + val: + min_dist[next_node] = temp_dist[cur_node] + val + if not visited[next_node]: + que.append(next_node) + visited[next_node] = True + k -= 1 + + if min_dist[dst] == inf: + print("unreachable") + else: + print(min_dist[dst]) + + if __name__ == "__main__": main() ```