The correct, optimal and working solution for programming question tree-height-of-a-binary-tree on hackerrank

/* * Author: Arpit Bhayani * http://arpitbhayani.me */ #include <cmath> #include <cstdio> #include <cstdlib> #include <climits> #include <deque> #include <iostream> #include <list> #include <limits> #include <map> #include <queue> #include <set> #include <stack> #include <vector> #define ll long long #define MIN(a, b) a < b ? a : b #define MAX(a, b) a > b ? a : b using namespace std; int readline(char *str) { int i = 0; char ch; while((ch = getchar()) != '\n') { str[i++] = ch; } str[i] = '\0'; return i; } struct node { int data; struct node * left; struct node * right; }; struct node * new_node(int v) { struct node * t = (struct node *) calloc(1, sizeof(struct node)); t->data = v; return t; } int max(int a, int b) { return (a > b) ? a : b; } int height(struct node * root) { if(root == NULL) { return -1; } return 1 + max(height(root->left), height(root->right)); } int main(int argc, char *argv[]) { struct node * root = new_node(3); root->left = new_node(2); root->left->left = new_node(1); root->right = new_node(5); root->right->left = new_node(4); root->right->right = new_node(6); root->right->right->right = new_node(7); printf("%d\n", height(root)); return 0; }