As the placement season is back so are we to help you ace the interview. We have selected some most commonly asked and must do practice problems for you.

You can also take part in our *mock placement contests* which will help you learn different topics and practice at the same time, simulating the feeling of a real placement test environment.

**Note : **Now you can track your progress of these questions **Must Do Interview Preparation Course**.

**Topic :**

- Arrays
- String
- Linked List
- Stack and Queue
- Tree and BST
- Heap
- Recursion
- Hashing
- Graph
- Greedy
- Dynamic Programming
- Divide and Conquer
- Backtracking
- Bit Magic

**Arrays :**

- Subarray with given sum
- Count the triplets
- Kadane’s Algorithm
- Missing number in array
- Merge two sorted arrays
- Rearrange array alternatively
- Number of pairs
- Inversion of Array
- Sort an array of 0s, 1s and 2s
- Equilibrium point
- Leaders in an array
- Minimum Platforms
- Reverse array in groups
- K’th smallest element
- Trapping Rain Water
- Pythagorean Triplet
- Chocolate Distribution Problem
- Stock buy and sell
- Element with left side smaller and right side greater
- Convert array into Zig-Zag fashion
- Last Index of 1
- Spirally traversing a matrix
- Largest Number formed from an Array

**Solved the above?** Go for some more Questions

**String :**

- Reverse words in a given string
- Permutations of a given string
- Longest Palindrome in a String
- Recursively remove all adjacent duplicates
- Check if string is rotated by two places
- Roman Number to Integer
- Anagram
- Remove Duplicates
- Form a Palindrome
- Longest Distinct Characters in the string
- Implement Atoi
- Implement strstr
- Longest Common Prefix

**Solved the above?** Go for some more Questions

**Linked List :**

- Finding middle element in a linked list
- Reverse a linked list
- Rotate a Linked List
- Reverse a Linked List in groups of given size
- Intersection point in Y shaped linked lists
- Detect Loop in linked list
- Remove loop in Linked List
- n’th node from end of linked list
- Flattening a Linked List
- Merge two sorted linked lists
- Intersection point of two Linked Lists
- Pairwise swap of a linked list
- Add two numbers represented by linked lists
- Check if Linked List is Palindrome
- Implement Queue using Linked List
- Implement Stack using Linked List
- Given a linked list of 0s, 1s and 2s, sort it
- Delete without head pointer

**Stack and Queue :**

- Parenthesis Checker
- Next larger element
- Queue using two Stacks
- Stack using two queues
- Get minimum element from stack
- LRU Cache
- Circular tour
- First non-repeating character in a stream
- Rotten Oranges
- Maximum of all subarrays of size k

**Tree :**

- Print Left View of Binary Tree
- Check for BST
- Print Bottom View of Binary Tree
- Print a Binary Tree in Vertical Order
- Level order traversal in spiral form
- Connect Nodes at Same Level
- Lowest Common Ancestor in a BST
- Convert a given Binary Tree to Doubly Linked List
- Write Code to Determine if Two Trees are Identical or Not
- Given a binary tree, check whether it is a mirror of itself
- Height of Binary Tree
- Maximum Path Sum
- Diameter of a Binary Tree
- Number of leaf nodes
- Check if given Binary Tree is Height Balanced or Not
- Serialize and Deserialize a Binary Tree

**Solved the above?** Go for some more Questions

**Heap :**

- Find median in a stream
- Heap Sort
- Operations on Binary Min Heap
- Rearrange characters
- Kth largest element in a stream
- Merge K sorted linked lists
- Kth largest element in a stream

**Recursion :**

**Hashing :**

- Relative Sorting
- Sorting Elements of an Array by Frequency
- Largest subarray with 0 sum
- Common elements
- Find all four sum numbers
- Swapping pairs make sum equal
- Count distinct elements in every window
- Array Pair Sum Divisibility Problem
- Longest consecutive subsequence
- Array Subset of another array
- Find all pairs with a given sum
- Find first repeated character
- Zero Sum Subarrays
- Minimum indexed character
- Check if two arrays are equal or not
- Uncommon characters
- Smallest window in a string containing all the characters of another string
- First element to occur k times
- Check if frequencies can be equal

**Graph :**

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