Build Blocks and Obstacles on a Number Line

Problem Overview

• Simulate two operations on an infinite number line: place an obstacle at x, or query if a block of size s fits from x without hitting obstacles.
• Input: array of operations [1,x] and [2,x,size]; obstacles are placed only on empty positions; queries do not modify the line.
• Output: a binary string (1/0) for each [2,x,size] feasibility check, in order.
• Domain: spatial fit checks and obstacle placement on a number line; typical coding interview problem.
• Source: Meta interviews; a practical interview question.