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LeetCode111. 二叉树的最小深度 (BFS) + (递归)两种方法

BFS

# 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        q = []        q.append(root)        ans = 1        while q:            tmp = []            for i in q:                if i.left:                    tmp.append(i.left)                if i.right:                    tmp.append(i.right)                if not i.left and not i.right:                    return ans            ans +=1            q = tmp        return ans

递归

# Definition for a binary tree node.# class TreeNode:#     def __init__(self, x):#         self.val = x#         self.left = None#         self.right = Noneclass Solution:    def minDepth(self, root: TreeNode) -> int:        if not root:            return 0        l = self.minDepth(root.left) + 1        r = self.minDepth(root.right) + 1        if root.left and root.right:            return min(l, r)        elif root.left:            return l        else:            return r

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