Problem
In a simplified Meta Messenger map, a 2D grid represents water and land, where '1' is land and '0' is water. Count how many distinct islands exist.
An island is a group of horizontally or vertically adjacent land cells. Cells connected diagonally do not belong to the same island.
Formal Specification
Write a function that takes grid, a list of lists of single-character strings ('0' or '1'), and returns an integer: the number of islands.
Constraints
- 1 <= len(grid) <= 300
- 1 <= len(grid[0]) <= 300
- grid[i][j] is either '0' or '1'
- Cells are connected only in 4 directions: up, down, left, right
- You may modify the input grid in place
Function Signature
def num_islands(grid):
Practicing as: Software Engineer interview at MetaHi, I'll play your Meta interviewer for the Software Engineer role. Candidates describe these interviews as mostly positive and hard, so expect me to be friendly but thorough. Take your time with the question above and answer like we're in the room.
You are practicing as a guest. Sign up free to run your code against the sample data. Your draft stays right here.
