Problem: Flood Fill. Task: you are given an image (a grid of integers). Each integer represents a color. You are given a starting coordinate (sr, sc) and a newColor. Replace the starting pixel and all connected pixels of the same color with the newColor.
This is your first application of DFS on grids. You will see how traversal translates from abstract graphs to concrete arrays. Think of each cell as a node and each pair of adjacent same-color cells as an edge.