LeetCode 797. All Paths From Source to Target

Description:

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.

Note:

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.

Solution:

class Path:
    last = None
    node = -1
    
    def __init__(self, last, node):
        self.last = last
        self.node = node

class Solution(object):
    
    def allPathsSourceTarget(self, graph):
        """
        :type graph: List[List[int]]
        :rtype: List[List[int]]
        """
        start = 0
        end = len(graph) - 1
        
        # bfs
        queue = []
        queue.append(Path(None, start))
        
        endNode = []
        
        while len(queue) > 0:
            front = queue.pop(0)
            assert front.node != -1
            
            if front.node == end:
                endNode.append(front)
            else:
                for nextNode in graph[front.node]:
                    queue.append(Path(front, nextNode))
        
        result = []
        for node in endNode:
            path = []
            obj = node
            while obj is not None:
                path.append(obj.node)
                obj = obj.last
            path.reverse()
            result.append(path)
        return result

Simple bredth first search algorithm.