Game Of Life · Interview Problem

Back to problems

Leetcode

Medium

Matrices

Arrays

Simulation

Google

Game Of Life

Update a 2D board one generation at a time using the rules of Conway's Game of Life.

Acceptance 100%

Start Practice

Problem Statement

You are given an $m \times n$ board where each cell is either alive (1) or dead (0). The board evolves in discrete steps according to the following rules:

Any live cell with fewer than 2 live neighbors dies, as if by underpopulation.
Any live cell with 2 or 3 live neighbors lives on.
Any live cell with more than 3 live neighbors dies, as if by overpopulation.
Any dead cell with exactly 3 live neighbors becomes alive, as if by reproduction.

A cell's neighbors are the 8 surrounding cells horizontally, vertically, and diagonally adjacent.

Modify the board in place to represent the next generation.

Input Format

A 2D integer array board of size m x n.
board[i][j] = 1 means the cell is alive, and 0 means it is dead.

Output Format

Update board in place so that it reflects the next state of the grid.
No separate return value is required in the in-place formulation.

Constraints

1 <= m, n
The grid is finite and cells outside the board are treated as dead.
Use only the current generation to determine the next one.

Examples

Sample cases returned by the problem API.

Example 1

Input

board = [[0,1,0],[0,0,1],[1,1,1],[0,0,0]]

Output

[[0,0,0],[1,0,1],[0,1,1],[0,1,0]]

Explanation

Apply the four rules to every cell simultaneously using the original board state. The resulting next generation is shown in the output.

Premium problem context

Unlock deeper context for this problem

Premium adds guided hints, editorial links, similar variants, discussion resources, and concept maps so you can understand why a problem matters, not just solve it once.

Guided hints

Editorial and discussion links

Concept map and variants

Track your progress