Create 190404-BST_Lowest_common_ancestor.md

PS/190404-BST_Lowest_common_ancestor.md

@@ -0,0 +1,70 @@
+# [Binary Search Tree : Lowest Common Ancestor](https://www.hackerrank.com/challenges/binary-search-tree-lowest-common-ancestor/problem?h_l=interview&playlist_slugs%5B%5D=interview-preparation-kit&playlist_slugs%5B%5D=trees)
+## Problem
+## Solve
+```java
+import java.util.*;
+import java.io.*;
+
+class Node {
+    Node left;
+    Node right;
+    int data;
+
+    Node(int data) {
+        this.data = data;
+        left = null;
+        right = null;
+    }
+}
+
+class Solution {
+
+	/*
+    class Node 
+    	int data;
+    	Node left;
+    	Node right;
+	*/
+	public static Node lca(Node root, int v1, int v2) {
+    if(root.data < v1 && root.data < v2){
+            return lca(root.right,v1,v2);
+        }
+        if(root.data > v1 && root.data > v2){
+            return lca(root.left,v1,v2);
+        }
+
+        return root;
+    }
+
+	public static Node insert(Node root, int data) {
+        if(root == null) {
+            return new Node(data);
+        } else {
+            Node cur;
+            if(data <= root.data) {
+                cur = insert(root.left, data);
+                root.left = cur;
+            } else {
+                cur = insert(root.right, data);
+                root.right = cur;
+            }
+            return root;
+        }
+    }
+
+    public static void main(String[] args) {
+        Scanner scan = new Scanner(System.in);
+        int t = scan.nextInt();
+        Node root = null;
+        while(t-- > 0) {
+            int data = scan.nextInt();
+            root = insert(root, data);
+        }
+      	int v1 = scan.nextInt();
+      	int v2 = scan.nextInt();
+        scan.close();
+        Node ans = lca(root,v1,v2);
+        System.out.println(ans.data);
+    }	
+}
+```