Program to find longest path between two nodes of a tree in Python

Suppose we have a binary tree; we have to find the longest path between any two nodes in the tree.

So, if the input is like

 then the output will be 5 

To solve this, we will follow these steps:

• ans := 0

• Define a function getMaxPath() . This will take node

• if node is null, then

  • return 0

• leftCnt := getMaxPath(left of node)

• rightCnt := getMaxPath(right of node)

• temp := 1 + maximum of leftCnt and rightCnt

• ans := maximum of ans and l+r+1

• From the main method do the following −

• getMaxPath(root)

• return ans

Let us see the following implementation to get better understanding −

Example

 Live Demo

class TreeNode:    def __init__(self, val, left=None, right=None):       self.val = val       self.left = left       self.right = right class Solution:    def solve(self, root):       self.ans = 0       def getMaxPath(root):          if root is None:             return 0          l = getMaxPath(root.left)          r = getMaxPath(root.right)          temp = max(l, r) + 1          self.ans = max(self.ans, l + r + 1)          return temp       getMaxPath(root)       return self.ans ob = Solution() root = TreeNode(2) root.left = TreeNode(10) root.right = TreeNode(4) root.right.left = TreeNode(8) root.right.right = TreeNode(2) root.right.left.left = TreeNode(6) print(ob.solve(root))

Input

root = TreeNode(2) root.left = TreeNode(10) root.right = TreeNode(4) root.right.left = TreeNode(8) root.right.right = TreeNode(2) root.right.left.left = TreeNode(6)

Output

5