- Minimum Depth of Binary Tree Easy
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Share Given a binary tree, find its minimum depth.
The minimum depth is the number of nodes along the shortest path from the root node down to the nearest leaf node.
Note: A leaf is a node with no children.
Example:
Given binary tree [3,9,20,null,null,15,7],
3
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/
9 20 /
15 7 return its minimum depth = 2.
思路:深度优先算法
代码:python3
# Definition for a binary tree node.
# class TreeNode:
# def __init__(self, x):
# self.val = x
# self.left = None
# self.right = None
class Solution:
def minDepth(self, root: TreeNode) -> int:
if not root:return 0
self.deep=float('inf')
def dfs(root,level):
if not root:return
if not root.left and not root.right:
self.deep=min(level,self.deep)
else:
dfs(root.left,level+1)
dfs(root.right,level+1)
dfs(root,1)
return self.deep
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tips: float('inf') 正无穷
转载于:https://juejin.im/post/5d09a81ae51d4577555508e7