Write a program to reverse a singly linked list? Modify that program to reverse a doubly linked list.
PHP Algorithm Interview Questions
Questions to ask a PHP Developer
PHP engineers are often required to have a knowledge of the full web stack: starting with the ability to write optimized SQL queries, and wrapping up with a good understanding of HTML/CSS. When interviewing a PHP developer, make sure that you think through your requirements and ask good questions for all of them.
Here's a suggestion for a good menu of PHP interview questions:
- Start off with some basic SQL such as SQL Skills: Joins, Averages and Sums
- Include at least one simple coding task such as Separate a list of integers or Find the missing number
- Explore their ability to come up with an overall system design and data model with a flexible question like Design a restaurant reservation system or Design a card game system
- Ensure that they have a solid understanding of the basic building blocks of the web by asking about HTTP GET and POST or What are HTTP cookies?
- Wrap up with some CSS questions like Explore the HTML display and position attributes or CSS rule-set basics
Assume that you have access to an employee's email Inbox, and that you can parse the content of their emails, including the email headers.
- How can you use this to deduce their first-degree connections?
- What kind of heuristics can you come up with to quantify the strength of these first-degree connections?
- How can you use this to deduce their second-degree connections?
- How can you use this to deduce their third-degree connections?
Suppose you have an array of 99 numbers. The array contains the digits 1 to 100 with one digit missing. Describe four different algorithms to compute the missing number. Two of these should optimize for low storage and two of these should optimize for fast processing.
Write a string to find a substring in a given string. Do this in O(n) or better
Write an iterative function to reverse a string. Do the same thing as a recursive function.
Write a function to implement strstr() i.e. find the first occurrence of one string inside another string.
Write a program to print out a multiplication table, from 1x1 to 12x12. This should look like:
1 2 3 4 5 6 7 8 9 10 11 12
2 4 6 8 10 12 14 16 18 20 22 24
3 6 9 12 15 18 21 24 27 30 33 36
4 8 12 16 20 24 28 32 36 40 44 48
5 10 15 20 25 30 35 40 45 50 55 60
6 12 18 24 30 36 42 48 54 60 66 72
7 14 21 28 35 42 49 56 63 70 77 84
8 16 24 32 40 48 56 64 72 80 88 96
9 18 27 36 45 54 63 72 81 90 99 108
10 20 30 40 50 60 70 80 90 100 110 120
11 22 33 44 55 66 77 88 99 110 121 132
12 24 36 48 60 72 84 96 108 120 132 144
Explain big o notation and how it is useful in computer science to classify algorithms.
- What order is a hash table lookup?
- What order is determining if a number is even or odd?
- What order is finding an item in an unsorted list?
- What order is a binary search?
Describe bitwise operators AND, OR, XOR and NOT. Describe how you might use these.
How do these bitwise operators differ from logical operators?
Write a program to find the largest integer in an array of integers.
Write a function that sums up integers from a text file that looks like the following:
1
3
27
2
2123
Write function to print the odd numbers from 1 to 99
If you have access to a function that returns a random integer from one to five, write another function which returns a random integer from one to seven.
Discuss an algorithm to traverse a tree, depth first.
Efficiently calculate the shortest distance between two Facebook users given an API endpoint that returns all friends of a given user.
Write a function that takes an integer and returns the smallest number that is greater than the given number which is a palendrome.
For example, if the input was 111 the next palindromic number would be 121.
Write a function, tokenize_string(input_string, delimiter_list) that returns a list of strings that are separated by the delimiters.
For example: tokenize_string("How now, Mrs. Brown Cow") returns ['How', 'now', 'Mrs', 'Brown', 'Cow']
Given two arrays of strings, A and B.
B contains every element in A, and has one additional member, for example:
* A = ['dog', 'cat', 'monkey]
* B = ['cat', 'rat', 'dog', 'monkey']
Write a function to find the extra string in B. Do this in O(n)
Write a function to return the Nth number of Fibonacci sequence.