PHP Advanced (Coding)

60 Minutes

4 Questions

This test evaluates a candidate's expertise in PHP, focusing on advanced programming concepts, data structures, and efficient data manipulation techniques. The assessment covers PHP syntax, object-oriented programming (OOP), functional programming, sorting and searching algorithms, and performance optimization. Candidates will be tested on their ability to write optimized, secure, and scalable PHP code, implementing efficient data structures and manipulation techniques in real-world scenarios. The test also includes challenges that assess a candidate's understanding of algorithmic efficiency, PHP's built-in functions, and best practices for high-performance applications.

Example Question:

Coding

You are given a binary string s of length n. Your task is to convert it to another string t by doing the following operation any number of times (including zero):

Choose an index such that the character to the left and right of this index is not equal, and flip the indexed character. Note that you cannot choose the first or last index.

A binary string consists only of the characters '0' and '1'. Flipping a character refers to changing '0' to '1' and vice versa. Find the minimum number of operations required to make the transformation. Return -1 if the transformation is impossible.

Example:

s = "0100"
t = "0010"

One sequence of operations that achieves the minimum number of operations is the following:

Select index=3, changing 0100 to 0110.
Select index=2, changing 0110 to 0010.

Hence, the answer is 2.