leetcode 797. All Paths From Source to Target(python3)

题目

Given a directed, acyclic graph of N nodes. Find all possible paths from node 0 to node N-1, and return them in any order.

The graph is given as follows: the nodes are 0, 1, …, graph.length - 1. graph[i] is a list of all nodes j for which the edge (i, j) exists.

``````Example:
Input: [[1,2], [3], [3], []]
Output: [[0,1,3],[0,2,3]]
Explanation: The graph looks like this:
0--->1
|    |
v    v
2--->3
There are two paths: 0 -> 1 -> 3 and 0 -> 2 -> 3.``````

Note:

• The number of nodes in the graph will be in the range [2, 15].
• You can print different paths in any order, but you should keep the order of nodes inside one path.

分析

代码块

``````class Solution:
def allPathsSourceTarget(self, graph):
""" :type graph: List[List[int]] :rtype: List[List[int]] """
for i in graph:
i.sort()
fianl = []  #存储最终返回的列表
a = [0]  #每次搜索均从0开始
def dfs(n,a):
for i in graph[n]:
a.append(i)
if i == len(graph)-1:
fianl.append(a[:])
a.pop()
print(a)
if i == graph[n][-1]:   #此次搜索到达该列表末尾，弹出末尾值
a.pop()
print(a)
return
else:
dfs(i, a)
if i == graph[n][-1]:
a.pop()

dfs(0, a)
return fianl
``````