gameoflife.js

/**
 * @param {number[][]} board
 * @return {void} Do not return anything, modify board in-place instead.
 */
var gameOfLife = function(board) {
    let neighbors = [0, 1, -1];
    let rows = board.length;
    let cols = board[0].length;
    let copyBoard = [];
    copyBoard.length = rows;
    
    for (let i = 0; i < rows; i++) {
        for (let j = 0; j < cols; j++) {
            if (!copyBoard[i]) {
                copyBoard[i] = [];
                copyBoard[i].length = cols;
            }
            copyBoard[i][j] = board[i][j];
        }
    }
    
    for (let row = 0; row < rows; row++) {
        for (let col = 0; col < cols; col++) {
            let liveNeighbors = 0;
            
            for (let i = 0; i < 3; i++) {
                for (let j = 0; j < 3; j++) {
                    if (!(neighbors[i] == 0 && neighbors[j] == 0)) {
                        let r = row + neighbors[i];
                        let c = col + neighbors[j];
                        
                        if ((r < rows && r >= 0) && (c < cols && c >= 0) && (copyBoard[r][c] == 1)) {
                            liveNeighbors += 1;
                        }
                    }
                }
            }
            
            if (copyBoard[row][col] == 1 && (liveNeighbors < 2 || liveNeighbors > 3)) {
                board[row][col] = 0;
            }
            
            if (!copyBoard[row][col] && liveNeighbors == 3) {
                board[row][col] = 1;
            }
        }
    }
};