543.二叉树的直径

class Solution(object): def diameterOfBinaryTree(self, root): self.ans = 0 def dfs(root): if not root: return 0 l = dfs(root.left) r = dfs(root.right) self.ans = max(self.ans,l+r+1) return max(l,r)+1 dfs(root) return self.ans-1

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