The correct, optimal and working solution for programming question bst-lca on hackerrank

/* * Author: Arpit Bhayani * https://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 data) { struct node * t = (struct node *) calloc(1, sizeof(struct node)); t->data = data; return t; } struct node * lca(struct node * root, int v1, int v2) { if(v1 > v2) { int t = v1; v1 = v2; v2 = t; } struct node * p = root; while(p) { if(p->data > v1 && p->data < v2) { return p; } if(p->data > v1 && p->data > v2) { p = p->left; } else if(p->data < v1 && p->data < v2) { p = p->right; } else { return p; } } return NULL; } int main(int argc, char *argv[]) { struct node * root = new_node(4); root->left = new_node(2); root->right = new_node(7); root->left->left = new_node(1); root->left->right = new_node(3); root->right->left = new_node(6); printf("%d\n", lca(root, 1, 7)->data); return 0; }