Hi guys, when we take the Data Structures or Algorithms study plans, we can't refer back to the questions once the stipulated days have ended. So, here's the list of questions in the Data Structures - 1 Study Plan:

Day 1 - Array
217. Contains Duplicate
53. Maximum Subarray

Day 2 - Array
1. Two Sum
88. Merge Sorted Array

Day 3 - Array
350. Intersection of Two Arrays - 2
121. Best Time to Buy and Sell Stock

Day 4 - Array
566. Reshape the Matrix
188. Pascal's Triangle

Day 5 - Array
36. Valid Sudoku
74. Search a 2D Matrix

Day 6 - String
387. First Unique Character in a String
383. Ransom Note
242. Valid Anagram

Day 7 - Linked Lists
141. Linked List Cycle
21. Merge Two Sorted Lists
203. Remove Linked List Elements

Day 8 - Linked List
206. Reverse Linked List
83. Remove Duplicates from Sorted List

Day 9 - Stack/Queue
20. Valid Parentheses
232. Implement Queue using Stacks

Day 10 - Tree
144. Binary Tree Preorder Traversal
94. Binary Tree Inorder Traversal
145. Binary Tree Postorder Traversal

Day 11 - Tree
102. Binary Tree Level Order Traversal
104. Maximum Depth of Binary Tree
101. Symmetric Tree

Day 12 - Tree
226. Invert Binary Tree
112. Path Sum

Day 13 - Tree
700. Search in a Binary Search Tree
701. Insert into a Binary Search Tree

Day 14 - Tree
98. Validate Binary Search Tree
653. Two Sum IV - Input is a BST
235. Lowest Common Ancestor of a Binary Search Tree