gameOfLife289

class Solution {
    //289. Game of Life
    //Time complexity: O(rows*columns)
    //Space complexity: O(1)
    int rows;
    int cols;
    public void gameOfLife(int[][] board) {
         rows = board.length;
         cols = board[0].length;
        for(int i = 0;i < rows;i++){
            for(int j =0; j < cols;j++){
                int count = liveCount(board,i,j);
                //making live cell dead
                //1---> 0 (3)
                if(board[i][j] ==1 && (count < 2 || count>3))
                    board[i][j] = 3;
                //making a dead cell --live
                //0--->1  (2)
                else if(board[i][j]== 0 && count==3)
                    board[i][j]=2;
            }
        }
        
         for(int i = 0;i < rows;i++){
            for(int j =0; j < cols;j++){
                if(board[i][j]==3)
                    board[i][j]=0;
                else if(board[i][j]==2)
                    board[i][j]=1;
            }
         }
    }
        
       private int liveCount(int[][] board,int i,int j){
           int count=0;
           int[][] dirs = {{0,-1},{0,1},{-1,0},{1,0},{-1,1},{-1,-1},{1,-1},{1,1}};
           for(int[] dir :dirs){
               int row = dir[0]+i;
               int col = dir[1]+j;
               if(row>=0 && col>=0 && row < rows && col < cols && (board[row][col]==1 || board[row][col]==3)){
                   count++;
               }
           
           }
           return count;
       }
    }