二叉树遍历bfs和dfs

最新推荐文章于 2024-08-18 17:46:51 发布

际遇98

最新推荐文章于 2024-08-18 17:46:51 发布

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分类专栏： python基础篇

本文链接：https://blog.youkuaiyun.com/qq_41629348/article/details/99286473

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本文深入探讨了广度优先搜索（BFS）和深度优先搜索（DFS）两种核心算法，通过具体实例展示了这两种算法在遍历树形结构数据时的工作原理。广度优先搜索从根节点开始，一层一层地遍历所有节点；而深度优先搜索则优先探索尽可能深的子树。文章提供了Python实现代码，帮助读者理解算法细节。

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广度优先

# bfs
class node(object):
    def __init__(self,key):
        self.key = key
        self.left = None
        self.right = None

root = node(5)
root.left = node(2)
root.right = node(4)
root.left.left = node(7)
root.right.left = node(3)
root.left.right = node(3)
root.right.right = node(6)

from collections import deque
def bfs(node):
    if node is None:
        return
    myset = set()  #seen
    myset.add(node.key) # root is seen
    myqueque = deque()
    myqueque.append(node)
    
    while len(myqueque) > 0:
        cur = myqueque.popleft()
        print(cur.key)
        
        if cur.left:
            if not cur.left.key in myset:
                myset.add(cur.left.key)
                myqueque.append(cur.left)
        if cur.right:
            if not cur.right.key in myset:
                myset.add(cur.right.key)
                myqueque.append(cur.right)

bfs(root)

5
2
4
7
3
6

深度优先

class node(object):
    def __init__(self,key):
        self.key = key
        self.next = []

# dfs
def dfs(node):
    if node is None:
        return 
    
    nodeset = set()
    stack = []
    print(node.key)
    nodeset.add(node)
    stack.append(node)
    while len(stack) > 0:
        cur = stack.pop()
        
        for next_ele in cur.nexts:
            if next_ele not in nodeset:
                stack.append(cur)
                stack.append(next_ele)
                set.add(next_ele)
                print(next_ele)
                break