Google - SWE - Onsite (Aug 2023)

Interview Experience
1

August 2023

Description Template:
Level: New Grad
Education: Bachelors
Years of Experience: 2
Questions Asked:

  1. Valid Perentheses

Given a string s containing just the characters '(', ')', '{', '}', '[' and ']', determine if the input string is valid.

An input string is valid if:

  1. Open brackets must be closed by the same type of brackets.
  2. Open brackets must be closed in the correct order.
  3. Every close bracket has a corresponding open bracket of the same type.

Example 1:

Input: s = “()”

Output: true

Example 2:

Input: s = “(){}”

Output: true

Example 3:

Input: s = “(]”

Output: false

Example 4:

Input: s = “()”

Output: true

  1. Find and Replace in string

You are given a 0-indexed string s that you must perform k replacement operations on. The replacement operations are given as three 0-indexed parallel arrays, indices, sources, and targets, all of length k.

To complete the ith replacement operation:

  1. Check if the substring sources[i] occurs at index indices[i] in the original string s.
  2. If it does not occur, do nothing.
  3. Otherwise if it does occur, replace that substring with targets[i].

For example, if s = "abcd", indices[i] = 0, sources[i] = "ab", and targets[i] = "eee", then the result of this replacement will be "eeecd".

All replacement operations must occur simultaneously, meaning the replacement operations should not affect the indexing of each other. The testcases will be generated such that the replacements will not overlap.

  • For example, a testcase with s = "abc", indices = [0, 1], and sources = ["ab","bc"] will not be generated because the "ab" and "bc" replacements overlap.

Return the resulting string after performing all replacement operations on s.

A substring is a contiguous sequence of characters in a string.