Bubble Popping Game

Problem Overview

• Simulate a bubble-popping game on a 2D grid and return the final grid after all operations.
• Inputs: a grid of bubble colors and a list of pop coordinates; Output: the grid state after processing in order.
• Rules: popping zero does nothing; popping a bubble also pops same-color diagonal neighbors within bounds; then gravity makes bubbles fall into empty cells.
• Context: models game mechanics in a bubble board setting.
• A classic coding interview problem and interview question on grid simulation.