Must Do Coding Questions in Java

Array

S.No	Question Link	Solution	Difficulty
1	Subarray with given sum	Subarray with given sum	Easy
2	Kadane's Algorithm	Kadane's Algorithm	Medium
3	Missing number in array	Missing number in array	Easy
4	Merge Without Extra Space	Merge Without Extra Space	Hard
5	Rearrange Array Alternately	Rearrange Array Alternately	Medium
6	Largest Number formed from an Array	Largest Number formed from an Array	Medium
7	Spirally traversing a matrix	Spirally traversing a matrix	Easy
8	Convert array into Zig-Zag fashion	Convert array into Zig-Zag fashion	Easy
9	Trapping Rain Water	Trapping Rain Water	Medium
10	Kth smallest element	Kth smallest element	Medium
11	Reverse array in groups	Reverse array in groups	Basic
12	Minimum Platforms	Minimum Platforms	Medium
13	Leaders in an array	Leaders in an array	Easy
14	Equilibrium Point	Equilibrium Point	Easy
15	Reverse Array	Reverse array	Easy
16	Sort 0 1 2	Sort 0 1 2	Easy

Searching Algo

S.No	Question Link	Solution	Difficulty
1	Linear Search	Linear Search	Basic
2	Binary Search	Binary Search	Basic

Sorting Algo

S.No	Question Link	Solution	Difficulty
1	Bubble Sort	Bubble Sort	Basic
2	Selection Sort	Selection Sort	Basic
3	Insertion Sort	Insertion Sort	Easy
4	Merge Sort	Merge Sort	Easy

String

S.No	Question Link	Solution	Difficulty
1	Longest Common Prefix in an Array	Longest Common Prefix in an Array	Medium
2	Reverse words in a given string	Reverse words in a given string	Easy
3	Permutations of a given string	Permutations of a given string	Basic
4	Longest Palindrome in a String	Longest Palindrome in a String	Medium
5	Roman Number to Integer	Roman Number to Integer	Easy
6	Convert to Roman No	Convert to Roman No r	Easy
7	Anagram	Anagram	Easy

LinkedList

S.No	Question Link	Solution	Difficulty
1	Finding middle element in a linked list	Finding middle element in a linked list	Basic
2	Reverse a linked list	Reverse a linked list	Easy
3	Rotate a Linked List	Rotate a Linked List	Easy
4	Reverse a Linked List in groups of given size	Reverse a Linked List in groups of given size	Medium
5	Intersection Point in Y Shapped Linked Lists	Intersection Point in Y Shapped Linked Lists	Medium
6	Detect Loop in linked list	Detect Loop in linked list	Easy
7	Nth node from end of linked list	Nth node from end of linked list	Easy
8	Merge two sorted linked lists	Merge two sorted linked lists	Easy
9	Add two numbers represented by linked lists	Add two numbers represented by linked lists	Easy
10	Check if Linked List is Palindrome	Check if Linked List is Palindrome	Easy
11	Flattening a Linked List	Flattening a Linked List	Medium
12	Given a linked list of 0s, 1s and 2s, sort it	Given a linked list of 0s, 1s and 2s, sort it	Easy
13	Remove duplicate	Remove duplicate	Easy

Tree

S.No	Question Link	Solution	Difficulty
1	Left View of Binary Tree	Left View of Binary Tree	Easy
2	Check for BST	Check for BST	Medium
3	Count Leaves in Binary Tree	Count Leaves in Binary Tree	Basic
4	Diameter of Binary Tree	Diameter of Binary Tree	Easy
5	Height of Binary Tree	Height of Binary Tree	Basic
6	Check for Balanced Tree	Check for Balanced Tree	Easy
7	Symmetric Tree	Symmetric Tree	Easy
8	Identical Tree	Identical Tree	Easy
9	Connect Nodes at Same Level	Connect Nodes at Same Level	Medium
10	Level order traversal in spiral form	Level order traversal in spiral form	Easy
11	Level order traversal	Level order traversal	Easy
12	Inorder Traversal	Inorder Traversal	Easy
13	Preorder Traversal	Preorder Traversal	Easy
14	Postorder Traversal	Postorder Traversal	Easy
15	Delete without head pointer	Delete without head pointer	Medium