least common ancestor

Author: manju07

Data-Structure/Tree/Binary Tree/LCA/LCA.js

@@ -0,0 +1,53 @@
+'use strict';
+class Node {
+    constructor(data) {
+        this.data = data;
+        this.leftNode = this.rightNode = null;
+    }
+}
+
+function LCA(root, data1, data2) {
+    if (root == null) return null;
+    if (root.data == data1 || root.data == data2) return root;
+    let leftLCA = LCA(root.leftNode, data1, data2);
+    let rightLCA = LCA(root.rightNode, data1, data2);
+    if (leftLCA != null && rightLCA != null) return root;
+    return leftLCA != null ? leftLCA : rightLCA;
+}
+
+//level - 1
+let tree = new Node(1);
+
+// level - 2
+tree.leftNode = new Node(2);
+tree.rightNode = new Node(3);
+
+// level - 3
+tree.leftNode.leftNode = new Node(4);
+tree.leftNode.rightNode = new Node(5);
+
+tree.rightNode.leftNode = new Node(6);
+tree.rightNode.rightNode = new Node(7);
+
+// level - 4
+tree.leftNode.leftNode.leftNode = new Node(8);
+tree.leftNode.leftNode.rightNode = new Node(9);
+
+tree.leftNode.rightNode.leftNode = new Node(10);
+tree.leftNode.rightNode.rightNode = new Node(11);
+
+tree.rightNode.leftNode.leftNode = new Node(12);
+tree.rightNode.leftNode.rightNode = new Node(13);
+
+tree.rightNode.rightNode.leftNode = new Node(14);
+tree.rightNode.rightNode.rightNode = new Node(15);
+//             1
+//         /       \
+//       2           3
+//     /   \       /   \
+//    4     5     6      7
+//   / \   / \   / \    / \
+//  8  9  10 11 12 13 14   15
+let k1 = 4, k2 = 10;
+let lcaNode = LCA(tree, k1, k2);
+console.log('LCA of ' + k1 + ' and ' + k2 + ' => ', lcaNode != null ? lcaNode.data : 0);