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Interview coding problems/challenges

Hey geeks! Up for solving the problems which are being asked in interviews?

Here you go...

We are trying to list out the most frequently asked interview problems or the problem given in the coding rounds of IT giants.

For you we have detailed analysis:

• A proper explanation of question with explanations so that you can have a nice idea of your own and can think about a solution yourself.
• A detailed explanation of the solution with a generalized algorithm so that you can code yourself without checking our codes given at the end.
• If still, you have issues to figure out a solution then step by step explanation of the code. A detailed explanation of how the code works with the example?
• Don't think you will need anything more!!

Benefits if you hit our Interview coding problems pages: Definitely, we may have better ad sense earning more you hit the pages. But it’s not actually for us. The more you hit, the more you practice, the more you get prepared. You have to do some serious coding if you need to get hired. All over the net, you are surely in a loop considering where to start from. Here are we to light you up and that’s why we chose and place the best problems here. Some may seem to be easy, some may seem to be tough. No, issue if it’s easy just check whether you have a more optimized solution or not. If you have a more optimized solution, then feel free to post in the comments. Remember sharing is caring!!

String

1. Run-length encoding (find/print frequency of letters in a string)
2. Checking Anagrams (check whether two string is anagrams or not)
3. Count and Say sequence
4. Longest Common Prefix
5. Count Substrings
6. Number following the pattern
7. Next Permutation
8. Convert Ternary Expression to Binary Tree
9. Count of strings that can be formed using a, b and c under given constraints
10. Minimum Number of Flips
11. Count Occurrences of Anagrams
12. Rearrange a string
13. Print bracket number
14. Longest Palindromic Subsequence
15. Preorder to Postorder of BST
16. Maximum difference of zeros and ones in binary string
17. Sum of all substrings of a number

Arrays

1. Sort an array of 0's, 1's and 2's in linear time complexity
2. Check for Valid Sudoku
3. Palindromic Array
4. Largest Fibonacci Subsequence
5. Pairs of songs with total durations divisible by 60
6. All subarray Sum of an array
7. Suggesting movie randomly from a list C++ program

Sorting

1. Sort an array of 0's, 1's and 2's in linear time complexity
2. Relative sorting algorithm

Searching

1. Finding First Bad Version
2. Maximum value in a bitonic array
3. Search for a Range

Coding Algorithms

1. Run-length encoding (find/print frequency of letters in a string)
2. Sort an array of 0's, 1's and 2's in linear time complexity
3. Finding subarray with given sum
4. 1[0]1 Pattern Count
5. Capitalize first and last letter of each word in a line
6. Greedy Strategy to solve major algorithm problems
7. Job sequencing problem
8. Exit Point in a Matrix
9. Generate Gray Code Sequences
10. Picking Numbers

Tree

1. Find the level in a binary tree with given sum K
2. Check whether a Binary Tree is BST (Binary Search Tree) or not
3. Print vertical sum of a binary tree
4. Print Boundary Sum of a Binary Tree
5. Root to leaf Path Sum
6. Print All Nodes that don't have Sibling
7. Two Mirror Trees
8. Transform to Sum Tree
9. Symmetric Tree
10. Convert Sorted Array to Binary Search Tree
11. Odd even level difference in a binary tree
12. Check if Tree is Isomorphic
13. Expression Tree
14. K distance from root
15. Right View of Binary Tree
16. Diameter of Binary Tree
17. Delete nodes greater than or equal to k in a BST
18. Reverse Level Order Traversal
19. Diagonal Traversal of Binary Tree
20. Leftmost and Rightmost Nodes of Binary Tree
21. Lowest Common Ancestor in a BST
22. Convert Ternary Expression to Binary Tree
23. Bottom View of Binary Tree
24. Ancestors in Binary Tree
25. All Root to Leaf Paths
26. Sum of all numbers formed by root to leaf path
27. Minimum distance between two given nodes of a Binary Tree
28. K-th smallest element in a Binary Search Tree
29. Level order traversal in spiral form
30. Maximum path sum in a binary tree
31. Preorder to Postorder of BST
32. Check Mirror in N-ary Tree

Stack

1. Number following the pattern
2. Print bracket number
3. Stock Span Problem
4. Redundant Bracket
5. Postfix Expression Evaluation
6. Largest rectangle area in a histogram
7. Minimum Add to Make Parentheses Valid
8. Check Mirror in N-ary Tree

Queue

1. Check Mirror in N-ary Tree

Linked list

1. Reverse a single linked list
2. Find length of loop in a linked list
3. Palindrome Linked List
4. Intersection Point in Y-Shaped Linked List
5. Absolute sorting on a single linked list
6. Sum of two numbers represented by linked lists

Graph

1. Rotten Oranges
2. Alien Dictionary
3. Find the number of islands
4. Check a graph is Hamiltonian or not (Hamiltonian path)
5. Knight walk problem
6. Floyd Warshall Algorithm
7. Minimum Spanning Tree

Binary search

1. Book Allocation Problem (Allocate minimum number of pages)

Greedy Algorithms

1. Greedy Strategy to solve major algorithm problems
2. Job sequencing problem
3. Fractional knapsack problem
4. Rain Water Trapping Problem

Dynamic Programming

1. 0-1 Knapsack Algorithm
2. House Robber
3. Coin Change
4. Minimum Coin Change | Find minimum number of coins that make a given value
5. Word Break Problem
6. Friends pairing problem
7. Maximum Profit in Stock Buy and sell with at most K Transaction
8. Floyd Warshall Algorithm
9. Optimal Strategy for a Game
10. Highway billboard
11. Gold Mine Problem
12. Longest Increasing Subsequence
13. Minimum Number of coins to make the change
14. Get Minimum Squares
15. Count Numbers with unique digits
16. Maximum Sum Problem
17. Find number of times a string occurs as a subsequence
18. Number of Unique Paths
19. Minimum number of jumps
20. Rod Cutting

More Dynamic Programming Practice Problems

Matrix

1. Exit Point in a Matrix
2. Shortest Source to Destination Path
3. Gold Mine Problem

Recursion

1. Palindromic Array
2. Wine selling problem | Find the maximum profit from sale of wines
3. Minimum Coin Change | Find minimum number of coins that make a given value
4. Egg Dropping Problem
5. Maximum path sum in a binary tree
6. Minimum number of deletions to make a sorted sequence
7. Jumbled Strings
8. Count of divisible array
9. Maximum Calorie
10. Special Keyboard
11. Minimal moves to form a string
12. Total number of non-decreasing numbers with n digits using dynamic programming
13. Minimum Time to Display N Character
14. Knapsack with Duplicate Items
15. Longest Common Subsequence of three strings
16. Minimum steps to minimize n as per given condition
17. Count total number of Palindromic Subsequences
18. Adjacent are not allowed
19. Count number of binary strings without consecutive 1's
20. Longest Palindromic Substring
21. Count total number of Palindromic Substrings

More Recursion Practice Problems...

Number theory

1. Sieve of Eratosthenes

Bitwise operators

1. Game of XOR

Puzzle

1. Prisoners and the poison

Combinatorics

1. Total number of non-decreasing numbers with n digits

Backtracking

1. String Matrix
2. Tug of War
3. Backtracking to find all subsets
4. Find out the sum-string
5. Power Set in Lexicographic order
6. Fill 8 numbers in a matrix
7. Partition a set into k subset with equal sum
8. Combinational sum problem
9. Combinational sum problem with repetition of digits
10. Match a pattern and String without using regular expressions
11. Warnsdorff's algorithm for Knight's tour problem

Iterative approach

1. Find the largest palindromic substring using O(1) space complexity

Trie Data Structure

1. Check the consistency of the numbers (Trie Data Structure Question)

Hash

1. Length of the largest subarray with equal number of 0s and 1s
2. Fencing Problem

Heap

1. Constructing the Array

Brute Force

1. Stock Span Problem
2. Rain Water Trapping Problem
3. Largest rectangle area in a histogram

Implementation

1. Redundant Bracket
2. Rain Water Trapping Problem
3. Longest Prefix and Suffix
4. Fencing Problem
5. Constructing the Array

Google contests

1. Nesting Depth - Google CodeJam 2020 qualification round problem solution
2. Vestigium - Google CodeJam 2020 qualification round problem1 solution

Miscellaneous

1. Find nth Magic number
2. Toppers of Class
3. Where is my seat?
4. Google CodeJam 2019 | Foregone Solution
5. Find the perfect land of C shape
6. Find the magic matrix

Others

1. Top 25 Dynamic programming problems for interviews
2. Company Wise Interview Questions