【广度优先搜索-中等】面试题 04.01. 节点间通路（Python版本两种解法bfs、dfs）

【题目】

【代码】
【方法1】思路：广度优先搜索bfs

class Solution:
    def findWhetherExistsPath(self, n: int, graph: List[List[int]], start: int, target: int) -> bool:
        dic={}
        for x,y in graph:
            if x not in dic:
                dic[x]=[]
            dic[x].append(y)
        queue=[start]
        while queue:
            item=queue.pop(0)
            if item==target:
                return True
            if item not in dic:
                continue
            for son in dic[item]:
                queue.append(son)
        return False

【方法2】思路：深度优先搜索dfs

class Solution:
    def findWhetherExistsPath(self, n: int, graph: List[List[int]], start: int, target: int) -> bool:
        dic={}
        for x,y in graph:
            if x not in dic:
                dic[x]=[]
            dic[x].append(y)
        def dfs(x,visited):
            if x==target:
                return True
            if visited[x]:
                return False
            visited[x]=True
            ans=False
            if x in dic:
                for son in dic[x]:
                    ans=ans or dfs(son,visited)
            return ans
        return dfs(start,[False]*n)