Guide to Interview Coding questions.

In this page I have listed all the coding questions that have been solved in this website.

Question 1: Given an array of integers in ascending order, return index of the two numbers such that they add up to a specific key provided.

Question 2: Given two non empty Linked List with non negative numbers, and numbers are stored in reverse order having single digit. Add the two list and return the result as a linked list.

Question 3: Count the number of ways a baby can reach the nth stair taking 1 or 2 steps at a time in C language.

Question 4: Sort an array of 0s, 1s and 2s in C

Question 5: Given an array, the difference between the elements is one, find if the “key” element is present or not.

Question 6: Given an unsorted array, find the minimum difference between 2 elements.

Question 7: Given an unsorted array, find the least difference between the element pairs. Display all the pairs present.

Question 8: Given an unsorted array, and a key. Find 2 elements such that the difference between the elements is equal to the key.

Question 9: Given an unsorted integer array, find the smallest missing positive integer.

Question 10: Given an array, find all the repeated elements in C language

Question 11: Given an integer value, convert it into roman number.

Question 12: Given a string, and number of rows, write the string in zigzag pattern.

Question 13: Given a string find the longest Palindromic Substring with detailed explanation and solution in C++.

Question 14: Given an input string (s) and a pattern (p), implement regular expression matching with support for ‘.’ and ‘*’.

Question 15: Find the Container with Most Water explanation with diagram and solution in cpp language

Question 16: Given an array of non repeating numbers and a key, find all the unique combinations in that array, where the sum of those combination is equal to the key.

Question 17: Given an array, find 3 elements such that [a + b + c] = 0. Find all the 3 unique elements.

Question 18: Given an array of n integers and an integer “key”, find three integers in the array such that the sum is closest to key.

Question 19: Given an array n integers and an integer key, are there four elements a, b, c, and d in the array such that a + b + c + d = key? Find all unique quadruplets in the array which gives the sum of key.

Question 20: Given a linked list Remove Nth Node From End of List

Question 21: Letter Combinations of a Phone Number, solution in C++

Question 22: You are given with n pairs of parentheses, generate all combinations of well-formed parentheses.

Question 23: Merge two sorted linked lists and return it as a new list in C

Question 24: Given linked list swap Nodes in Pairs, solution in C++

Question 25: Divide two integers without using multiplication, division and mod operator

Question 26: Implement next permutation, which rearranges numbers into the next greater permutation of numbers.

Question 27: Given an array sorted in ascending order and is rotated at some pivot, given a target value to search, if found in the array return its index

Question 28: Merge k sorted linked lists and return it as one sorted list in C++

Question 29: Given a collection of candidate numbers and a key, find all unique combinations in candidates where the candidate numbers sums to target

Question 30: Given a collection of distinct integers, return all possible permutations C++ solution

Question 31: Given two non-negative integers num1 and num2 represented as strings, return the product of num1 and num2, also represented as a string

Question 32: Given a collection of numbers that might contain duplicates, return all possible unique permutations in C++

Question 33: Given an n x n 2D matrix rotate it by 90 degrees (clockwise) in C++ in place

Question 34: Group Anagrams when given an array of strings in C++

Question 35: Rain water trapping in C++

Question 36: Implement pow(x, n), which calculates x raised to the power n (x^n) in C++

Question 37: Given a matrix of m x n elements , print all elements of the matrix in spiral order in CPP

Question 38: Given an array of non-negative integers determine if you are able to reach the last index in C++

Question 39: Merge overlapping Intervals solution in C++

Question 40: Reverse Linked List iterative and recursive in C++

Question 41: Given a positive integer n, generate a square matrix filled with elements from 1 to n^2 in spiral order in C++

Question 42: Wildcard Matching in C++

Question 43: Find Intersection of Two Linked Lists in c++

Question 44: Rotate linked list by k nodes in C++

Question 45: Find path from top right to bottom left with Solution in C++

Question 46: Find path from top right to bottom left with obstacles in C++

Question 47: Minimum Cost Path in CPP

Question 48: Given an absolute path for a file (linux-style), simplify it CPP

Question 49: Reach the end of the array with minimum jumps. Solution in C++

Question 50: Given a m x n matrix, if an element is 0, set its entire row and column to 0. Do it in-place in CPP

Question 51: Given a 2D Matrix and a key element, search and return if element is present or not in C++

Question 52: Given an array with element colored red, white or blue, sort them in-place, with the colors in the order red, white and blue in CPP

Question 53: Given two integers n and k, return all possible combinations of k numbers out of 1 … n in CPP

Question 54: Given a set of distinct integers, nums, return all possible subsets in CPP

Question 55: Given 2D matrix and a word, find if the word exists in the grid in C++

Question 56: N-Queens in CPP

Question 57: Given a sorted array, remove duplicate elements in-place in CPP

Question 58: you are given an sorted array with repeated elements that is rotated at some point, return true or false if you find the key element in C++

Question 59: Given a linked list with duplicates, remove the nodes with duplicates and keep only distinct numbers, with solution in CPP

Question 60: You are given a linked list and a key “x”, partition the list in such a way that, all the nodes less than “x” comes before the nodes greater than or equal to “x” solution in CPP

Question 61: You are given a positive number “n”, print the sequence of grey code solution in CPP

Question 62: Given array of integers that might contain duplicates, return all the subsets. Solution in CPP

Question 63: Check if a given string is a valid number in CPP

Question 64: you are given a string having digits, convert into the string by looking at the table given below, solution in C++

Question 65: Reverse Linked List given 2 points m and n, solution in CPP

Question 66: Given a string of integers, restore all valid IP addresses solution in C++

Question 67: Given an array of non overlapping integers, insert a new interval by merging them, solution in C++

Question 68: Given a positive integer, generate pascal triangle, solution in C++

Question 69: Given a positive number “k” return the row of that index of pascals triangle, solution in C++

Question 70: Check if the given board is valid Sudoku or not, explanation with solution in C++

Question 71: Find minimum path from top to bottom in a triangle solution with explanation in C++

Question 72: Optimum Time to Buy and Sell Stock for maximum profit explanation with solution in C++

Question 73: Word Ladder explanation with solution in CPP

Question 74: Given a non-empty array, all the elements appears twice except for one, find that element.

Question 75: Given a string return all the substring that is a palindrome, solution in CPP

Question 76: Given a 2D board with X and O, get all the region surrounded by X, explanation in CPP

Question 77: Check if there is a gas stations along a circular route, solution with explanation in CPP

Question 78: Solve Sudoku, explanation in CPP

Question 79: Given an array every element appears three times except for one. Find that single one. Solution in C++

Question 80: Given a linked list such that each node contains an additional random pointer which could point to any node in the list or null. Return the deep copy of the list, solution in C++

Question 81: Given a string s and a dictionary wordDict containing a list of non-empty words, determine if s can be seperated into a space-separated sequence of one or more dictionary words. Solution in C++

Question 82: Given a linked list, check if it has a cycle in it, solution in C++

Question 83: Given a linked list, if it has a cycle, get the node where the cycle begins else return NULL.

Question 84: Given a sentence and maxWidth. Arrange the text in such a way that each line has exactly maxWidth characters, solution in C++

Question 85: Reorder list in to alternate nodes like first lowest and first highest. Solution in C++

Question 86: Given a linked list, sort the list using insertion sort. Solution with explanation

Question 87: Create a data structure for n elements and constant operations

Question 88: Given an array and a number n, rotate the array by n steps to its right solution in C++

Question 89: Given a string, reverse all the vowels in the string , solution in C++

Question 90: Given an array, check if it has any duplicate elements, 2 solutions in CPP

Question 91: Given a sorted array, find the starting and ending index that matches the target – 2 solutions using C++

Question 92: Given an array that is sorted and a target, if the target is found, return the index. If not found, return the index where it would be if it were inserted, 2 solutions in C++

Question 93: Given an array, find the continuous sub array that has the largest sum, return the sum. 2 solutions in C++

Question 94: 1’s and 2’s complement of a Binary Number

Question 95: Add and subtract 2 numbers using bitwise operators. C++ Solution

Question 96: Calculate the square of a number and also check if that number is even or odd using bitwise operator.

Question 97: Check if the number has bits in alternate pattern and also check if the same number has equal number of set and unset bits using bitwise operators.

Question 98: Given 2 numbers check if one number is complement of another and also check if those two numbers are same using bitwise operators.

Question 99: Perform below operations using Bitwise Operators

Question 100: Perform below swapping operations using Bitwise operators

Question 101: Perform multiplication operation using Bitwise operators

Question 102: Perform binary search on a singly linked list, solution in C++

Question 103: Perform bubble sort on singly linked list, solution in C++

Question 104: Perform below operations on Circular Singly Linked List, solution in C++

Question 105: Perform below delete operations from single linked list, solution in C++

Question 106: Perform below delete operations from single linked list, solution in C++

Question 107: Given an unsorted linked list, sort the list using merge sort, solution in C++

Question 108: Given an expression in reverse polish notation, evaluate it and get the output in C++

Question 109: You are given a sentence, reverse the string word by word in C++

Question 110: Given an integer array, find the maximum product made from continuous elements in that array. Solution in C++

Question 111: Find the minimum element from an array that is sorted and is rotated, solution in C++

Question 112: Given an array, find the majority element, solution in C++

Question 113: Given 2 strings, check if they are isomorphic strings, solution in C++

Question 114: Given an array and a key element, find the number of continuous elements whose sum is greater than the key element, solution in C++

Question 115: Dynamic Programming: Longest Increasing Subsequence

Question 116: Dynamic Programming: Longest Bitonic Subsequence

Question 117: Dynamic Programming: Get Max Coin In Game problem.

Question 118: Dynamic Programming: Rod Cutting Problem

Question 119: Dynamic Programming: Box Stacking Problem

Question 120: Dynamic Programming: Building Bridges

Question 121: Dynamic Programming: Egg Dropping Problem

Question 122: Dynamic Programming: Min Edit Distance

Question 123: Bottom view of binary Tree

Question 124: Boundary Traversal of Binary Tree

Question 125: Top view of a binary tree

Question 126: Left view and right view of a Binary Tree

Question 127: Level Order Traversal

Question 128: Vertical Order Traversal

Question 129: Height or Max depth of a BTree

Question 130: Spiral order or Zigzag traversal of a Binary Tree

Question 131: Diameter of a Binary Tree

Question 132: Lowest Common ancestor of a Binary Tree.

Question 133: Check if 2 nodes are mirror of each other

Question 134: Check if two binary tree are identical

Question 135: Check if binary tree is a sum tree

Question 136: Add all the node values in a Binary Tree or Sum of a Binary tree

Question 137: Print the number of leaf nodes in a binary tree

Question 138: Print all the paths from root node to leaf node

Question 139: Print the nodes at k distance from the root of a binary tree

Question 140: Reverse Bits

Question 141: Count the number of set bits

Question 142: Power of 2

Question 143: Missing Number

Question 144: Counting set bits in a number

Question 145: Hamming Distance

Question 146: Bitwise and of number range

Question 147: Binary search on an array that is in descending order

Question 148: Order-Agnostic Binary Search

Question 149: Find the first and last occurrence of an element

Question 150: Find the number of times a Sorted array is Rotated

Question 151: Searching in a Nearly Sorted Array

Question 152: Find Floor of an element in a Sorted Array

Question 153: Find Ceil of an element in a Sorted Array

Question 154: Find position of an element in an Infinite Sorted Array

Question 155: Find the index of first 1 in an infinite sorted array of 0s and 1s

Question 156: Peak Element

Question 157: Find maximum element in Bitonic Array

Question 158: Search An Element in Bitonic Array

Question 159: Get the rotation count in sorted rotated array

Question 160: Count the number of 1’s in an array sorted in decreasing order.

Question 161: Binary Tree: Get difference between values at Even and Odd level in a binary tree

Question 162: Binary Tree: Get Number of Nodes in a Binary Tree

Question 163: Binary Tree: Display nodes at given level in Binary Tree

Question 164: Binary Tree: Display Reverse Level Order Traversal by using queue

Question 165: Binary Tree: Perform PreOrder traversal on a Binary Tree by without Recursion

Question 166: Binary Tree: Perform InOrder traversal on a Binary Tree by without Recursion

Question 167: Binary Tree: Perform PostOrder traversal on a Binary Tree by without Recursion

Question 168: Binary Tree: Convert a binary tree to its Mirror Tree

Question 169: Binary Tree: Delete a binary tree

Question 170: Binary Tree: Get Level of a Given Node

Question 171: Binary Tree: Get Sum of elements Level wise in a Binary Tree

Question 172: Binary Tree: Get Maximum width of Binary Tree

Question 173: Binary Tree: Display elements between any two given level

Question 174: Binary Tree: Check if binary tree is a height balanced tree?

Question 175: Binary Tree: Check if all Leaf Nodes are at same level in Binary tree

Question 176: Binary Tree: Find Parent of a given node value in Binary Tree

Question 177: Binary Tree: Check if given Binary Tree is BST

Question 178: Binary Tree: Find Sibling node of a given node value in Binary Tree

Question 179: Binary Tree: Check if given two nodes are siblings to each other in Binary Tree

Question 180: Binary Tree: Get Sum of all nodes formed from Root to Leaf Path

Question 181: Binary Tree: Get Average of all nodes in Binary Tree

Question 182: Binary Tree: Get Sum of all Leaf Nodes in Binary Tree

Question 183: Binary Tree: Find Maximum or Minimum in Binary Tree

Question 184: Binary Tree: Check if Binary Tree is Foldable Tree

Question 185: Binary Tree: Check if two Binary Trees are Isomorphic

Question 186: Binary Tree: Get Vertical Sum of Binary Tree

Question 187: Binary Tree: Get deepest Left Leaf Node in Binary Tree

Question 188: Binary Tree: Get depth of Odd level which contains Leaf node in Binary Tree

Question 189: Binary Tree: Display all the leaf nodes from left to right and right to left in a tree

Question 190: Binary Tree: Get count Non-Leaf nodes in a Binary Tree

Question 191: Binary Tree: Get the count full nodes in a Binary

Question 192: Binary Tree: Check if Two Trees are Mirror Structure to each other

Question 193: Arrays: Find numbers with even number of digits

Question 194: Arrays: Find unique numbers that sum upto zero

Question 195: Arrays: Find the k’th smallest/largest element in an array

Question 196: Arrays: Check If N and Its Double Exist

Question 197: Arrays: Move all the negative number in beginning

Question 198: Arrays: Find the union and intersection of two sorted arrays

Question 199: Arrays: Given an array, rotate it one time

Question 200: Arrays: Minimize the maximum difference between the heights

Question 201: Arrays: Given an array find the duplicate number

Question 202: Arrays: Merge Two Sorted arrays without using extra space

Question 203: Arrays: Inversion Count in an Array

Question 204: Arrays: Find common element in 3 sorted arrays.

Question 205: Arrays: Rearrange the array with one positive and one negative number.

Question 206: Arrays: Check if 3 consecutive odds exist

Question 207: Arrays: Merge sorted array inplace

Question 208: Arrays: Find whether an array is subset of another array

Question 209: Arrays: Find a triplet that sum to a given value

Question 210: Arrays: Find triplet with minimum sum

Question 211: Arrays: Three way partitioning of an array around a given range

Question 212: Arrays: Minimum swaps required to bring all elements less than or equal to k together

Question 213: Arrays: Get minimum number of merge operations to make an array palindrome

Question 214: Arrays: Find the median of 2 sorted arrays of same size

Question 215: Arrays: Program to check if an Array is Palindrome or not

Question 216: Matrix: Find median in a row wise sorted matrix.

Question 217: Matrix: Find a row with maximum number of 1’s in a binary matrix

Question 218: Matrix: Get the common elements in all row of a matrix.

Question 219: Strings: Reverse a string

Question 220: Strings: Remove all consecutive duplicates from the string

Question 221: Strings: Print all the duplicates in a string

Question 222: Strings: Given a string convert into its equivalent ASCII form

Question 223: Strings: Program to check if strings are rotations of each other or not

Question 224: Strings: Second most repeated word in a sequence

Question 225: Strings: Longer Contiguous Segments of Ones than Zeros

Question 226: Strings: Given a string, print all the subsequence

Question 227: Strings: Permutations of a given string

Question 228: Strings: Divide binary string into sub strings with equal number of 0s and 1s.

Question 229: Strings: Check balanced parenthesis

Question 230: Strings: Convert a string into its mobile numeric keypad

Question 231: Strings: Get the minimum number of inversions needed to make an expression balanced

Question 232: Strings: Count the number of string in 2D character array

Question 233: Strings: Convert Roman Numerals to Decimal

Question 234: Strings: Longest Common Prefix

Question 235: Strings: Minimum number of flips to make binary string alternate

Question 236: Strings: Minimum swaps required for bracket balancing

Question 237: Strings: Find the first repeated word in a string

Question 238: Strings: Find the longest common subsequence between two strings.

Question 239: Strings: Smallest distinct window

Question 240: Strings: Recursively print all sentences that can be formed from list of word lists

Question 241: Searching and Sorting: Get the fixed point in an array

Question 242: Searching and Sorting: Maximum and minimum of an array using minimum number of comparisons

Question 243: Searching and Sorting: Find the majority element in the array

Question 244: Searching and Sorting: Search an array where adjacent differ by at most k

Question 245: Searching and Sorting: Count all distinct pairs with difference equal to k

Question 246: Searching and Sorting: Maximum sum such that no two elements are adjacent

Question 247: Searching and Sorting: Merge 2 sorted arrays

Question 248: Searching and Sorting: print all subarrays with 0 sum

Question 249: Searching and Sorting: Product of array except itself

Question 250: Searching and Sorting: Sort Integers by The Number of 1 Bits

Question 251: Searching and Sorting: Minimum number of swaps required to sort an array

Question 252: Searching and Sorting: Find the smallest and second smallest elements in an array

Question 253: Searching and Sorting: K-th Element of Two Sorted Arrays

Question 254: Searching and Sorting: Factorial Trailing Zeroes

Question 255: Searching and Sorting: Find the missing number in Arithmetic Progression

Question 256: Linked List: Reverse Linked List in groups

Question 257: Linked List: Remove duplicates from an unsorted linked list

Question 258: Linked List: Move last element to front of a given Linked List

Question 259: Linked List: Add 1 to the linked list

Question 260: Linked List: Find middle element in Linked List

Question 261: Linked List: Split circular Linked List into two halves

Question 262: Linked List: Program to Check if a Singly Linked List is Palindrome

Question 263: Linked List: Deletion from a Circular Linked List

Question 264: Linked List: Reverse a Doubly Linked List

Question 265: Linked List: Find pairs with a given sum in a DLL.

Question 266: Linked List: Count triplets in a sorted DLL whose sum is equal to given value “k”.

Question 267: Linked List: Sort a “k”sorted Doubly Linked list

Question 268: Linked List: Rotate Doubly linked list by N nodes

Question 269: Linked List: Rotate a Doubly Linked list in group of Given Size

Question 270: Linked List: Flatten a Linked List

Question 271: Linked List: Multiply two numbers represented by Linked Lists

Question 272: Linked List: Delete nodes which have a greater value on right side using recursion

Question 273: Linked List: Segregate even and odd nodes in a Linked List

Question 274: Linked List: Odd Even Linked List

Question 275: Binary Trees: Diagonal Traversal of a Binary tree

Question 276: Binary Trees: Convert Binary tree into Sum tree

Question 277: Binary Trees: Construct Binary Tree from preorder and inorder traversal

Question 278: Binary Trees: Minimum swap required to convert binary tree to binary search tree

Question 279: Binary Trees: Convert Binary Tree to DLL

Question 280: Binary Trees: Find Duplicate Subtrees

Question 281: Binary Trees: Find largest subtree sum in a tree

Question 282: Binary Search Trees: Find a value in a BST

Question 283: Binary Search Trees: Deletion of a node in a BST

Question 284: Binary Search Trees: Find min and max value in a BST

Question 285: Binary Search Trees: Find the Inorder predecessor and successor for a given key in BST

Question 286: Binary Search Trees: A program to check if a binary tree is BST or not

Question 287: Binary Search Trees: Convert a BST into greater sum tree

Question 288: Binary Search Trees: LCA in a BST

Question 289: Binary Search Trees: Construct BST from preorder traversal

Question 290: Binary Search Trees: Convert Binary Tree into Binary Search Tree.

Question 291: Binary Search Trees: Convert a normal BST into a Balanced BST

Question 292: Binary Search Trees: Merge Two balanced BST

Question 293: Binary Search Trees: Kth Largest Element in a BST

Question 294: Binary Search Trees: Kth smallest Element in a BST

Question 295: Binary Search Trees: Return the sum of given range in BST.

Question 296: Binary Search Trees: Get the Shortest distance between two nodes in BST

Question 297: Binary Search Trees: Count the number of BST nodes that lie in a given range.

Question 298: Binary Search Trees: Convert sorted DLL to Balanced BST

Question 299: Binary Search Trees: Find triplet sum in BST

Question 300: Binary Search Trees: Check if the pre-order is a valid BST

Question 301: Binary Search Trees: Check if the BST has a dead end

Question 302: Binary Search Trees: Correct a BST where 2 nodes are swapped

Question 303: Binary Search Trees: Flatten BST to sorted list

Question 304: Greedy: Remove duplicates from a string

Question 305: Greedy: Add elements in an array so the sum is equal to the given range

Question 306: Greedy: Remove k digits from an number to make it a smallest integer.

Question 307: Greedy: Get the minimum platforms needed to avoid delay in the train arrival.

Question 308: Greedy: Check if the string is a substring of another string

Question 309: Greedy: Remove overlapping intervals.

Question 310: Greedy: Plant n flowers in flower bed

Question 311: Greedy: Maximum meetings in one room

Question 312: Greedy: Distribute Candy

Question 313: Greedy: Shuffle array so that one array element is greater than other array element

Question 314: Greedy: Schedule task efficiently

Question 315: Greedy: Maximum sum of absolute difference of an array

Question 316: Greedy: Maximum sum of absolute difference of an array

Question 317: Greedy: Juice change

Question 318: Greedy: Given a string, split into balanced strings.

Question 319: Greedy: Perform operations on a broker calculator

Question 320: Greedy: Add minimum to make parentheses valid.

Question 321: Greedy: Remove covered intervals.

Question 322: Greedy: Reduce the array size to the half

Question 323: Greedy: String break problem

Question 324: Greedy: Connect ropes with minimum cost.

Question 325: Greedy: Find maximum sum possible equal sum of three stacks

Question 326: Backtracking: Partition string into its palindrome

Question 327: Backtracking: You are given an array with repeated elements and a key element, find all unique combination to the key

Question 328: Backtracking: Get the k combination from an array of 1 to n

Question 329: Backtracking: Find combination sum of k numbers that sum up to n

Question 330: Backtracking: Letter case permutation

Question 331: Backtracking: Return the number of queens possible in a chessboard

Question 332: Backtracking: Get the sequential digits from the given range

Question 333: Backtracking: Partition to K Equal Sum Subsets

Question 334: Matrix: Find pair with maximum sum in the matrix.

Question 335: Matrix: Kth smallest element in a sorted matrix

Question 336: Strings: Minimum Number of Swaps to Make the Binary String Alternating

Question 337: Strings: Longest Substring Of All Vowels in Order

Question 338: Strings: Word Break Problem

Question 339: Strings: Check if it is possible to re-arrange characters in a string, such a way that no two adjacent are same

Question 340: Strings: Check if Word Equals Summation of Two Words

Question 341: Strings: Minimum Window Substring

Question 342: Strings: Remove all consecutive duplicates from the string

Question 343: Strings: Longest Prefix Suffix

Question 344: Strings: Find minimum operations required to transform a string into another string

Question 345: Strings: Number of Different Integers in a String

Question 346: Binary Trees: Check if a given graph is tree or not

Question 347: Binary Trees: Maximum Sum of nodes in Binary tree such that no two are adjacent

Question 348: Binary Trees: Kth Ancestor of a Tree Node

Question 349: Binary Trees: Find Duplicate Subtrees

Question 350: Backtracking: Get maximum sum in a matrix

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