diff --git a/src/hackerrank/interview_preparation_kit/search/swap_nodes_algo.ts b/src/hackerrank/interview_preparation_kit/search/swap_nodes_algo.ts
index 19fd178d..5e4476c9 100644
--- a/src/hackerrank/interview_preparation_kit/search/swap_nodes_algo.ts
+++ b/src/hackerrank/interview_preparation_kit/search/swap_nodes_algo.ts
@@ -23,7 +23,7 @@ export class Tree {
     this.buildTree(indexes);
   }
 
-  buildTree(indexes: number[][]): Tree {
+  buildTree(indexes: number[][]): this {
     const indexesCopy = [...indexes];
     let currentLevel = __INITIAL_LEVEL__;