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BST-LCA Solution

/*
*  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 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;
}