Practice makes perfect

//1.Find the most frequent integer in an array

2.Find pairs in an integer array whose sum is equal to 10 (bonus: do it in linear time)

3.Given 2 integer arrays, determine of the 2nd array is a rotated version of the 1st array. Ex. Original Array A={1,2,3,5,6,7,8} Rotated Array B={5,6,7,8,1,2,3}

4.Write fibbonaci iteratively and recursively (bonus: use dynamic programming)

//5.Find the only element in an array that only occurs once.

6.Find the common elements of 2 int arrays

7.Implement binary search of a sorted array of integers

8.Implement binary search in a rotated array (ex. {5,6,7,8,1,2,3})

9.Use dynamic programming to find the first X prime numbers

10.Write a function that prints out the binary form of an int

11.Implement parseInt

12.Implement squareroot function

13.Implement an exponent function (bonus: now try in log(n) time)

14.Write a multiply function that multiples 2 integers without using *

15.HARD: Given a function rand5() that returns a random int between 0 and 5, implement rand7()

16.HARD: Given a 2D array of 1s and 0s, count the number of "islands of 1s" (e.g. groups of connecting 1s)

Strings

17.Find the first non-repeated character in a String

18.Reverse a String iteratively and recursively

19.Determine if 2 Strings are anagrams

//20.Check if String is a palindrome 20. Bonus: generate palindromes 20. CHALLENGE: generate palindromatic squares like the wikipedia page

21.Check if a String is composed of all unique characters

22.Determine if a String is an int or a double

23.HARD: Find the shortest palindrome in a String

24.HARD: Print all permutations of a String

25.HARD: Given a single-line text String and a maximum width value, write the function 'String justify(String text, int maxWidth)' that formats the input text using full-justification, i.e., extra spaces on each line are equally distributed between the words; the first word on each line is flushed left and the last word on each line is flushed right

Trees

//26.Implement a BST with insert and delete functions

27.Print a tree using BFS and DFS

28.Write a function that determines if a tree is a BST

29.Find the smallest element in a BST

30.Find the 2nd largest number in a BST

31.Given a binary tree which is a sum tree (child nodes add to parent), write an algorithm to determine whether the tree is a valid sum tree

32.Find the distance between 2 nodes in a BST and a normal binary tree

33.Print the coordinates of every node in a binary tree, where root is 0,0

34.Print a tree by levels

35.Given a binary tree which is a sum tree, write an algorithm to determine whether the tree is a valid sum tree

36.Given a tree, verify that it contains a subtree.

37.HARD: Find the max distance between 2 nodes in a BST.

38.HARD: Construct a BST given the pre-order and in-order traversal Strings

Stacks, Queues, and Heaps

39.Implement a stack with push and pop functions

40.Implement a queue with queue and dequeue functions

41.Find the minimum element in a stack in O(1) time

42.Write a function that sorts a stack (bonus: sort the stack in place without extra memory)

43.Implement a binary min heap. Turn it into a binary max heap

44.HARD: Implement a queue using 2 stacks

Linked Lists

45.Implement a linked list (with insert and delete functions)

46.Find the Nth element in a linked list

47.Remove the Nth element of a linked list

48.Check if a linked list has cycles

49.Given a circular linked list, find the node at the beginning of the loop. Example: A-->B-->C --> D-->E -->C, C is the node that begins the loop

50.Check whether a link list is a palindrome

51.Reverse a linked list iteratively and recursively

Sorting

52.Implement bubble sort

53.Implement selection sort

54.Implement insertion sort

55.Implement merge sort

56.Implement quick sort