# 脸熟 E4 上门过经

E4 地点 MPK

Onsite

1. determine if the given string is a valid integer.
This is very similar to AtoI but an easier version - https://leetcode.com/problems/string-to-integer-atoi/
2. What is the complexity of finding the max value of an element in an array
Big O, Big Theta, Big Omega

Design a live reload feature for Instagram comments (new comments appear instantly)

1. Given an array find if it is monotonically increasing or not
https://leetcode.com/problems/monotonic-array/
2. Find the contiguous subarray sum equal to K
https://leetcode.com/problems/continuous-subarray-sum/ however negatives were allowed in the input

1. Behavioral questions like greatest technical challenge, interpersonal challenge, etc
2. Given an array of words, find which pairs of words form palidromes

1. Find a binary tree’s boundary(perimeter) nodes
https://leetcode.com/problems/boundary-of-binary-tree/
2. Count the number of islands in a 2D array (diagonal movements allowed)
https://leetcode.com/problems/number-of-islands/ , went into indepth discussion of iterative vs recursive solution, and optimizing recursive calls (bounds checking before recursing)

1. Add two numbers
https://leetcode.com/problems/add-two-numbers/ the digits were stored in a list and in non-reverse order. Could be negative numbers ex ["-",“1”,“3”]
2. Subtract two numbers
Same as above but subtracting the two numbers instead of adding