Question

Given a 2d grid map of '1's (land) and '0's (water), count the number of islands. An island is surrounded by water and is formed by connecting adjacent lands horizontally or vertically. You may assume all four edges of the grid are all surrounded by water.

Answer 1

A 2D grid represents a map with '1's as land and '0's as water. The number of islands is computed by using algorithms like DFS or BFS to traverse the grid and count connected groups of '1's, interpreted as landmasses. Each standalone group is considered an island.

Step-by-step explanation:

The question refers to a computational problem often found in the field of computer science, specifically in algorithms related to graph theory and matrix manipulation. The task is to count the number of islands in a given 2D grid map, where '1' represents land and '0' represents water. An island is defined as a group of adjacent '1's connected horizontally or vertically, but not diagonally, and completely surrounded by water.

To count the number of islands, a common algorithmic approach involves using Depth-First Search (DFS) or Breadth-First Search (BFS) to traverse the grid. When a '1' is encountered, the entire connected landmass is explored, marking visited parts to avoid recounting. Once the landmass is fully traversed, the count of islands is incremented. The algorithm continues until all cells of the grid have been examined.

This task is akin to creating a coastal topographic map where technologists, similar to geologists, would map out various features of a landscape. Here, the features are islands of '1's within a sea of '0's.