Machine Learning Engineer · Full Journey · Coding

Palo Alto Networks — Machine Learning Engineer ✅ Passed

Level: Senior-Level

Round: Full Journey · Type: Coding · Difficulty: 5/10 · Duration: 120 min · Interviewer: Neutral

Topics: Binary Search, Arrays, In-place Hashing

Location: San Francisco Bay Area

Interview date: 2025-12-28

Summary

Interview Rounds Overview

• Round 1: Coding
• Round 2: Coding

Details

I was asked two coding questions.

Question 1: Search Insert Position

The prompt was:

Given a sorted array of distinct integers and a target value, return the index if the target is found. If not, return the index where it would be if it were inserted in order.

Example 1:

Input: nums = [1,3,5,6], target = 5 Output: 2

Example 2:

Input: nums = [1,3,5,6], target = 2 Output: 1

Example 3:

Input: nums = [1,3,5,6], target = 7 Output: 4

My code:

` def searchInsert(nums, target): left, right = 0, len(nums) - 1

while left <= right:
    mid = (left + right) // 2

    if nums[mid] == target:
        return mid
    elif nums[mid] < target:
        left = mid + 1
    else:
        right = mid - 1

return left

`

Question 2: Find All Numbers Disappeared in an Array

The prompt was:

Given an array nums of n integers where nums[i] is in the range [1, n], return an array of all the integers in the range [1, n] that do not appear in nums.

Example 1:

Input: nums = [4,3,2,7,8,2,3,1] Output: [5,6]

Example 2:

Input: nums = [1,1] Output: [2]

My code:

` def findDisappearedNumbers(nums): for i in range(len(nums)): index = abs(nums[i]) - 1 nums[index] = -abs(nums[index])

return [i + 1 for i in range(len(nums)) if nums[i] > 0]

`

Hints:

• Question 1: Standard binary search. return left is the key (insertion position).
• Question 2: Use the array itself as a hash (index marking). Time complexity O(n), space complexity O(1) (very classic).

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