added description

Author: mauricechouam

Lowest Common Ancestor of a Binary Tree/code.js

@@ -0,0 +1,30 @@
+/*
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+/*
+ * @param {TreeNode} root
+ * @param {TreeNode} p
+ * @param {TreeNode} q
+ * @return {TreeNode}
+ */
+var lowestCommonAncestor = function(root, p, q) {
+    let currNode = root
+      
+      if (currNode === null) return currNode
+      
+      if (currNode.val == p.val || currNode.val == q.val) {
+          return currNode
+      }
+      
+      let lVal = lowestCommonAncestor(currNode.left, p, q)
+      let rVal = lowestCommonAncestor(currNode.right, p, q)
+      
+      if (lVal !== null && rVal !== null) return currNode
+      if (lVal === null && rVal === null) return null
+      
+      return lVal || rVal
+  };