Practice interview for general interview questions, answered in python 2.7, mostly tested with pytest
General
- Find the most frequent integer in an array
- Find pairs in an integer array whose sum is equal to 10 (bonus: do it in linear time)
- 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}
- Write fibbonaci iteratively and recursively (bonus: use dynamic programming)
- Find the only element in an array that only occurs once.
- Find the common elements of 2 int arrays
- Implement binary search of a sorted array of integers
- Implement binary search in a rotated array (ex. {5,6,7,8,1,2,3})
- Use dynamic programming to find the first X prime numbers
- Write a function that prints out the binary form of an int
- Implement parseInt
- Implement squareroot function
- Implement an exponent function (bonus: now try in log(n) time)
- Write a multiply function that multiplies 2 integers without using *
- HARD: Given a function rand5() that returns a random int between 0 and 5, implement rand7()
- HARD: Given a 2D array of 1s and 0s, count the number of "islands of 1s" (e.g. groups of connecting 1s)
Strings
- Find the first non-repeated character in a String
- Reverse a String iteratively and recursively
- Determine if 2 Strings are anagrams
- Check if String is a palindrome
- Check if a String is composed of all unique characters
- Determine if a String is an int or a double
- HARD: Find the shortest palindrome in a String
- HARD: Print all permutations of a String
- 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
- Implement a BST with insert and delete functions
- Print a tree using BFS and DFS
- Write a function that determines if a tree is a BST
- Find the smallest element in a BST
- Find the 2nd largest number in a BST
- 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
- Find the distance between 2 nodes in a BST and a normal binary tree
- Print the coordinates of every node in a binary tree, where root is 0,0
- Print a tree by levels
- Given a binary tree which is a sum tree, write an algorithm to determine whether the tree is a valid sum tree
- Given a tree, verify that it contains a subtree.
- HARD: Find the max distance between 2 nodes in a BST.
- HARD: Construct a BST given the pre-order and in-order traversal Strings
Stacks, Queues, and Heaps
- Implement a stack with push and pop functions
- Implement a queue with queue and dequeue functions
- Find the minimum element in a stack in O(1) time
- Write a function that sorts a stack (bonus: sort the stack in place without extra memory)
- Implement a binary min heap. Turn it into a binary max heap
- HARD: Implement a queue using 2 stacks
Linked Lists
- Implement a linked list (with insert and delete functions)
- Find the Nth element in a linked list
- Remove the Nth element of a linked list
- Check if a linked list has cycles
- 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
- Check whether a link list is a palindrome
- Reverse a linked list iteratively and recursively
Sorting
- Implement bubble sort
- Implement selection sort
- Implement insertion sort
- Implement merge sort
- Implement quick sort