Beginner Exercism • javascript

Game Of Life

Challenge Overview

After each generation, the cells interact with their eight neighbors, which are cells adjacent horizontally, vertically, or diagonally.

Introduction

Conway’s Game of Life is a fascinating cellular automaton created by the British mathematician John Horton Conway in 1970.

The game consists of a two-dimensional grid of cells that can either be “alive” or “dead.”

After each generation, the cells interact with their eight neighbors via a set of rules, which define the new generation.

Instructions

After each generation, the cells interact with their eight neighbors, which are cells adjacent horizontally, vertically, or diagonally.

The following rules are applied to each cell:

Any live cell with two or three live neighbors lives on.
Any dead cell with exactly three live neighbors becomes a live cell.
All other cells die or stay dead.

Given a matrix of 1s and 0s (corresponding to live and dead cells), apply the rules to each cell, and return the next generation.

Source: Exercism javascript/game-of-life

💡 View Solution

export const tick = (matrix) => {
  const rows = matrix.length;
  if (rows === 0) return [];
  const cols = matrix[0].length;
  const result = Array.from({ length: rows }, () => Array(cols).fill(0));

  for (let r = 0; r < rows; r++) {
    for (let c = 0; c < cols; c++) {
      let liveNeighbors = 0;
      for (let dr = -1; dr <= 1; dr++) {
        for (let dc = -1; dc <= 1; dc++) {
          if (dr === 0 && dc === 0) continue;
          const nr = r + dr;
          const nc = c + dc;
          if (nr >= 0 && nr < rows && nc >= 0 && nc < cols) {
            liveNeighbors += matrix[nr][nc];
          }
        }
      }

      if (matrix[r][c] === 1) {
        result[r][c] = (liveNeighbors === 2 || liveNeighbors === 3) ? 1 : 0;
      } else {
        result[r][c] = (liveNeighbors === 3) ? 1 : 0;
      }
    }
  }

  return result;
};