- 3: Find the majority element.
- 2: Minimum numbers of candies required.
- 1: Minimum flips to turn all the bulbs on.

- 2: Find the duplicate number in an array
- 1: Remove duplicates from a sorted array without extra space.

- 2: Minimum letters to be added at the beginning to make palindrome.
- 1: Letter combinations from numbers of a keypad.

- 3: Find the maximum sum of the array after K negations.
- 2: Can the circular trip be completed with given fuel and cost?
- 1: Jumping steps in the array.

- 5: Find the maximum path sum of a binary tree.
- 4: Find the diameter of a binary tree.
- 3: Check if a binary tree is a binary search tree.
- 2: Convert a binary tree into a doubly linked list, in place.
- 1: Implement a file syncing algorithm for a low-bandwidth network