DSA

Pattern

• print triangle pattern
• print diamond pattern
• print hollow square pattern
• print reverse triangle pattern
• print pyramid pattern

Array

• max element in array
• second max element in array
• check if array is sorted
• count number of elements that have at least one element greater than itself
• find unique element in array
• find missing number in array
• max sum of sub array
• print all sub arrays
• Remove Duplicates from Sorted Array
• move all zeros to end of array
• find sub array with given sum
• rotate array by one
• rotate array by given number
• leaders in array (question: 16 17 4 3 5 2, answer: 17 5 2)
• maximum difference between two elements in array such that larger element appears after smaller element
• stock buy sell to maximize profit
• max consecutive ones in binary array
• maximum length even odd sub array
• equilibrium index
• find a sub array of size k with the least average
• 3 sum

Math

• sum of digits of a number
• power of a number
• fibonacci series
• armstrong number (question: 153 = 1^3 + 5^3 + 3^3)
• print all divisors of a number
• GCD of two numbers
• count number of digits in a number
• check if a number is prime or not
• check if a number is palindrome or not
• count trailing zeros in factorial of a number

Matrix

• matrix row sum
• matrix column sum
• rotate matrix by 90 degree

Stack

• Stack implementation using array
• reverse a string using stack
• parenthesis matching using stack

Queue

• Queue implementation using array

Searching

• linear search
• binary search
• square root of a number
• return indices of two numbers whose sum is equal to given number
• find first and last occurrence of a number in sorted array
• search in rotated sorted array
• count number of occurrences in sorted array
• search in infinite sorted array

Bit Manipulation

• given a number, set its i'th bit
• given a number, clear its i'th bit
• given a number, toggle its i'th bit
• given a number, check if its i'th bit is set or not
• given a number, count number of set bits
• given array of numbers, every number occurs twice except one, find that number

Sorting

• bubble sort
• selection sort
• insertion sort
• merge sort
• quick sort

• Problems:

  • merge Two sorted array
  • intersection of two sorted array
  • union of two sorted array

String

Recursion

• print numbers from n to 1
• print numbers from 1 to n
• power of a number
• print binary form of a number
• reverse a string
• array sum using recursion
• flatten array using recursion
• string palindrome using recursion
• string permutation
• array permutation
• Given m, n count number of ways to reach from (0, 0) to (m, n) in a matrix
• letter combination of a phone number
• find the first index if element in array or -1 if not present
• find the last index if element in array or -1 if not present
• get all subsequences of a string
• generate parenthesis
• decode ways
• given a rope of length n, find the maximum number of pieces you can make such that the length of each piece is in set {a, b, c}
• maxPieces
• tower of hanoi
• K-th Symbol in Grammar
• Find the Winner of the Circular Game

hashing

• find pair of elements in array whose sum is equal to given number
• Find first non-repeating character of given String
• Remove duplicates from Array
• Intersection of Two Arrays
• check if arr[i] + arr[j] = arr[k] + arr[l]
• count number of sub arrays sum equals k

Linked List

• Singly Linked List implementation
• Doubly Linked List implementation
• Circular Linked List implementation

Binary Search Tree

• insert node in BST
• in order traversal
• pre order traversal
• post order traversal
• level order traversal
• search node in BST
• height of BST
• balanced BST

backtracking

• string permutation
• Maximum Length of a Concatenated String with Unique Characters

Dynamic Programming

Two Pointer

• pair of elements in sorted array whose sum is equal to given number
• count number of connective numbers that equal to num
• sort array of 0s & 1s