Given a binary tree, you need to compute the length of the diameter of the tree. The diameter of a binary tree is the length of the longest path between any two nodes in a tree. This path may or may not pass through the root.

Example:

Given a binary tree 

1         / \        2   3       / \           4   5

 

Return 3, which is the length of the path [4,2,1,3] or [5,2,1,3].

Note: The length of path between two nodes is represented by the number of edges between them.

 

# Definition for a binary tree node.# class TreeNode(object):#     def __init__(self, x):#         self.val = x#         self.left = None#         self.right = Noneclass Solution(object):    def diameterOfBinaryTree(self, root):        """        :type root: TreeNode        :rtype: int        """        self.ans=1        def dfs(node):            if not node:                return 0            L=dfs(node.left)            R=dfs(node.right)            self.ans=max(self.ans,L+R+1)            return max(L,R)+1        dfs(root)        return self.ans-1