797. 所有可能的路径

代码一：DFS回溯

class Solution(object):
    # 方法一：DFS
    def allPathsSourceTarget(self, graph):
        """
        :type graph: List[List[int]]
        :rtype: List[List[int]]
        """
        if not graph[0]:
            return []
        res = []
        n = len(graph)
        self.dfs(graph, 0, n - 1, [0], res)
        return res

    def dfs(self, graph, cur, end, temp, res):
        # 递归出口：当前节点是n-1时，说明找到一条新路径
        if temp[-1] == end:
            res.append(temp)
            return
        # 顺着当前节点往下走
        for i in graph[cur]:
            self.dfs(graph, i, end, temp + [i], res)

代码二：BFS

class Solution(object):
    def allPathsSourceTarget(self, graph):
        """
        :type graph: List[List[int]]
        :rtype: List[List[int]]
        """
        # 特判
        if not graph[0]:
            return []
        # 路径终点
        end = len(graph) - 1
        res = []
        # 队列初始化
        nodeQueue = [0]
        pathQueue = [[0]]
        while nodeQueue:
            node = nodeQueue.pop(0)
            path = pathQueue.pop(0)
            # 遍历当前节点能达到的所有节点
            for i in graph[node]:
                # 若当前节点是终点，则找到一条新路径
                if i == end:
                    res.append(path + [i])
                # 否则，当前节点先入队，并更新当前路径
                else:
                    nodeQueue.append(i)
                    pathQueue.append(path + [i])
        return res