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Determine reachability and optimize task scheduling

Last updated: Mar 29, 2026

Quick Overview

This question evaluates understanding of discrete reachability and resource-constrained scheduling, testing the ability to reason about iterative coordinate transformations and to optimize parallel task assignment under type and memory limits.

  • Medium
  • Amazon
  • Coding & Algorithms
  • Software Engineer

Determine reachability and optimize task scheduling

Company: Amazon

Role: Software Engineer

Category: Coding & Algorithms

Difficulty: Medium

Interview Round: Take-home Project

##### Question LeetCode 780. Reaching Points: Given four integers a, b, c, d (1 <= a, b, c, d <= 1000). Starting from (a, b) you may repeatedly apply either operation (x, y) → (x + y, y) or (x, y) → (x, x + y). Determine whether you can reach exactly (c, d). Return True or False. Given an array taskMemory of n positive integers (memory per task), an array taskType of n positive integers (task type), and an integer maxMemory. Each task takes 1 unit of time. The server can process at most two tasks in parallel only if they are the same type and together require no more than maxMemory units. Find the minimum total time required to process all tasks. https://leetcode.com/problems/reaching-points/description/

Quick Answer: This question evaluates understanding of discrete reachability and resource-constrained scheduling, testing the ability to reason about iterative coordinate transformations and to optimize parallel task assignment under type and memory limits.

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Amazon
Aug 4, 2025, 10:55 AM
Software Engineer
Take-home Project
Coding & Algorithms
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0
Question

LeetCode 780. Reaching Points: Given four integers a, b, c, d (1 <= a, b, c, d <= 1000). Starting from (a, b) you may repeatedly apply either operation (x, y) → (x + y, y) or (x, y) → (x, x + y). Determine whether you can reach exactly (c, d). Return True or False. Given an array taskMemory of n positive integers (memory per task), an array taskType of n positive integers (task type), and an integer maxMemory. Each task takes 1 unit of time. The server can process at most two tasks in parallel only if they are the same type and together require no more than maxMemory units. Find the minimum total time required to process all tasks.

https://leetcode.com/problems/reaching-points/description/

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