https://github.com/codedge/coding-challenges
Some coding challenges I came across in job interviews. Solutions are in PHP and Go.
https://github.com/codedge/coding-challenges
coding-challenge coding-challenges go golang job-interviews mask ordinal-numbers php
Last synced: 5 months ago
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Some coding challenges I came across in job interviews. Solutions are in PHP and Go.
- Host: GitHub
- URL: https://github.com/codedge/coding-challenges
- Owner: codedge
- Created: 2021-02-23T14:27:37.000Z (over 4 years ago)
- Default Branch: master
- Last Pushed: 2024-12-30T23:43:15.000Z (9 months ago)
- Last Synced: 2025-04-20T00:38:13.721Z (6 months ago)
- Topics: coding-challenge, coding-challenges, go, golang, job-interviews, mask, ordinal-numbers, php
- Language: PHP
- Homepage:
- Size: 93.8 KB
- Stars: 14
- Watchers: 2
- Forks: 3
- Open Issues: 7
-
Metadata Files:
- Readme: README.md
- Funding: .github/FUNDING.yml
Awesome Lists containing this project
README
A repository of coding challenges/tasks I came across in various job interviews.
I mostly do backend programming in Go and PHP, so here you can find some solutions.
The solutions to the tasks do not fulfill to be the shortest, fastest or cleanest solutions.
## Tasks
Each task should come with a solution plus some tests to verify.
### Task 1
Create a function `maskify` to mask digits of a credit card number with `#`.
**Requirements:**
- Do not mask the first digit and the last four digits
- Do not mask non-digit chars
- Do not mask if the input is less than 6
- Return '' when input is empty
### Task 2
Create a function `number_to_ordinal` to create an ordinal number for a given input.
Ordinal numbers in English have something like `st`, `nd`, `rd`, etc.
**Requirements:**
- Apply for number 1 to 1001... if that works any given number will do ;-)
### Task 3
Create a calculator for [Reverse Polish Notation](https://en.wikipedia.org/wiki/Reverse_Polish_notation).
Write a `calculate` function that accepts an input and returns the result of the operation.
**Requirements:**
- Support the mathematical operations for `+`, `-`, `*` and `/`
- Check for invalid syntax, like `2 3+`. There is a space missing.
- Return 0 (integer) when nothing is entered
- Return the numeric value when no operand is given, like `1 2 3.5` return `3.5`
### Task 4
Given you have an array of numbers, you move inside the array by the value of the current element.
Write a function `jump_out_of_array` that outputs
- the amount of jumps until you jump out of the array
- `-1` when you reach the end of the array but do not jump out
**Requirements:**
- Array size is indefinite
- Array elements are integers, positive and negative
**Example:**
Given an array of `A[2, 3, -1, 1, 6, 4]`.
- Jump 1: `A[0]` + `2` = `A[2]`
- Jump 2: `A[2]` + `(-1)` = `A[1]`
- Jump 3: `A[1]` + `3` = `A[4]`
- Jump 4: `A[4]` + `6` = out of range
So the result is `4`, you need `4` jumps to jump out of the array.
### Task 5
Find the k-complement pairs in an array of a given number. Write a function `k_complement` that that outputs the amount
of pairs.
**Requirements:**
_Do not_ use nested loops to solve this problem, because of a time complexity of the loop solution.
[Check this thread](https://stackoverflow.com/questions/11032015/how-to-find-time-complexity-of-an-algorithm) to see what time complexity of an algorithm means.
**Example:**
- `A[0]` + `A[8]` = `1` + `5` = `6`
- `A[1]` + `A[6]` = `8` + `-2` = `6`
- `A[4]` + `A[8]` = `1` + `5` = `6`
- `A[5]` + `A[5]` = `3` + `3` = `6`
- `A[5]` + `A[5]` = `3` + `3` = `6`
- `A[6]` + `A[1]` = `-2` + `8` = `6`
- `A[8]` + `A[0]` = `5` + `1` = `6`
The result here is `7`.
### Task 6
Calculate the [Fibonacci number](https://en.wikipedia.org/wiki/Fibonacci_number) of a given number
and return the last `6` non-zero numbers.
**Requirements:**
- Use a recursive approach instead of looping through.
- Throw an exception when passing in a negative number
**Example:**
- `F8` = `21`, return `21`
- `F38` = `39088169`, return `88169`
### Task 7
Given the follwing function you should suggest what could be improved. There are no other documents explaining why this function has been written or what the purpose is/should be.
**Example in python**
```python
def multiply(x, y):
if y > 0:
return (1 + multiply(x, y-1))
else:
return 0
```
**Possible considerations:**
- Does the function really _multiply_ two values?
- Could the in-built multiply function be used?
- Is a recursive function the way to go?
- What can happen when using this with big numbers, f. ex. > 1.000.000?
- Type hints
### Task 8
Do an in-place mirroring of a one dimensional array. In-place switching is key here as the input array can be very big
and no additional memory should be occupied - see [Space Complexity](https://www.geeksforgeeks.org/g-fact-86/).
**Requirements:**
- In-place mirroring
- Handle array with even and odd amount of items
- Do not use the [`array_reverse`](https://www.php.net/manual/de/function.array-reverse.php) function in PHP
**Example:**
- Even amount: `[8,5,1,4]` -> `[4,1,5,8]`
- Odd amount: `[6,2,7,9,3]` -> `[3,9,7,2,6]`
## Contribute
Feel free to contribute. Use the issue list to propose new tasks or open PRs. Just provide proper tests
and description and requirements for the tasks.