LeetCode 289. Game of Life

November 6, 2024

Final matrix problem, this one a bit special to me. My first repo in Github is for a Game of Life program in C++. I created it in 2011 as a science fair project.

Solution

This method uses constant space by usind integer division and modulo operations. We use this to update state in-place, then we traverse over the grid again to convert the values back to 0 or 1.

1class Solution:
2    def gameOfLife(self, board: List[List[int]]) -> None:
3        """
4        Do not return anything, modify board in-place instead.
5        """
6        neighbors = [(-1, -1), (-1, 0), (-1, 1), (0, -1), (0, 1), (1, -1), (1, 0), (1, 1)]
7        for i, row in enumerate(board):
8            for j, cell in enumerate(row):
9                neighborCount = 0
10                for (nx, ny) in neighbors:
11                    y, x = i + ny, j + nx
12                    if (x >= 0 and y >= 0 and
13                        x < len(board[0]) and y < len(board) and
14                        board[y][x] % 2):
15                        neighborCount += 1
16                if cell % 2 and neighborCount < 2:
17                    pass
18                elif cell % 2 and neighborCount == 2 or neighborCount == 3:
19                    board[i][j] += 2
20                elif cell % 2 and neighborCount > 3:
21                    pass
22                elif not cell % 2 and neighborCount == 3:
23                    board[i][j] += 2
24        
25        for i in range(len(board)):
26            for j in range(len(board[0])):
27                board[i][j] = board[i][j] // 2
28``
29(n) = m * n

LeetCode 48. Rotate Image

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