Diameter of a Binary Tree | Recursive optimized C program to find the diameter of a Binary Tree ; A binary tree node has data , pointer to left child and a pointer to right child ; Helper function that allocates a new node with the given data and NULL left and right pointers . ; returns max of two integers ; The function Compute the " height " of a tree . Height is the number f nodes along the longest path from the root node down to the farthest leaf node . ; base case tree is empty ; If tree is not empty then height = 1 + max of left height and right heights ; Function to get diameter of a binary tree ; base case where tree is empty ; get the height of left and right sub - trees ; get the diameter of left and right sub - trees ; Return max of following three 1 ) Diameter of left subtree 2 ) Diameter of right subtree 3 ) Height of left subtree + height of right subtree + 1 ; Driver Code ; Constructed binary tree is 1 / \ 2 3 / \ 4 5 ; Function Call
#include <bits/stdc++.h> NEW_LINE using namespace std ; struct node { int data ; struct node * left , * right ; } ; struct node * newNode ( int data ) { struct node * node = ( struct node * ) malloc ( sizeof ( struct node ) ) ; node -> data = data ; node -> left = NULL ; node -> right = NULL ; return ( node ) ; } int max ( int a , int b ) { return ( a > b ) ? a : b ; } int height ( struct node * node ) { if ( node == NULL ) return 0 ; return 1 + max ( height ( node -> left ) , height ( node -> right ) ) ; } int diameter ( struct node * tree ) { if ( tree == NULL ) return 0 ; int lheight = height ( tree -> left ) ; int rheight = height ( tree -> right ) ; int ldiameter = diameter ( tree -> left ) ; int rdiameter = diameter ( tree -> right ) ; return max ( lheight + rheight + 1 , max ( ldiameter , rdiameter ) ) ; } int main ( ) { struct node * root = newNode ( 1 ) ; root -> left = newNode ( 2 ) ; root -> right = newNode ( 3 ) ; root -> left -> left = newNode ( 4 ) ; root -> left -> right = newNode ( 5 ) ; cout << " Diameter ▁ of ▁ the ▁ given ▁ binary ▁ tree ▁ is ▁ " << diameter ( root ) ; return 0 ; }