Amazon Coding Round Interview Questions

• Given an array of distinct elements and a number x, find if there is a pair with product equal to x.
• Given a string ‘str’ of digits and an integer ‘n’, build the lowest possible number by removing ‘n’ digits from the string and not changing the order of input digits.
• Given a number, find its corresponding Roman numeral.

Amazon System Design Interview Questions

• Design a system that controls traffic lights with below assumptions:
• A group of traffic lights has two components: main lights and pedestrian lights.
• Main traffic lights has three colors: red, yellow and green.
• Pedestrian lights has two colors: red and green.
• Pedestrian lights’ colors are reversed from main lights:
  • Main: red/yellow – pedestrian’s: green
  • Main: green – pedestrian: red
• There is a button for pedestrian lights if the button is pushed in advance, pedestrian’s lights change colors according to the main ones if the button isn’t pushed, pedestrian’s lights remain red.
• A typical junction has 4 groups of lights.
• Additional question: design the system in a way that allows cars which start from one junction after a red light don’t have to stop at the next one.