https://qiita.com/kaityo256/items/b2e504c100f4274deb42#comment-96c94c0965eb7fe939c8

maze.py

import sys
import random


def show_maze(maze):
    print()
    for row in maze:
        print(' ', *row, sep='')


def maze(height, width):
    """height行width列の迷路を作る"""
    maze = [['*'] * (width * 2 + 1) for y in range(height * 2 + 1)]
    clusters = [number for number in range(height * width)]

    def clusterling(cluster1, cluster2):
        """大きい方のクラスタ番号を小さい方のクラスタ番号にリンクする"""
        clusters[max(cluster1, cluster2)] = min(cluster1, cluster2)

    def cluster(x1, y1):
        """指定位置のクラスタ番号(接続先最小クラスタ番号)を得る"""
        number = y1 * width + x1
        while number != clusters[number]:
            number = clusters[number]
        return number

    def remove(wall):
        """指定された壁を壊してクラスタリング"""
        x1, y1, x2, y2 = wall
        c1 = cluster(x1, y1)
        c2 = cluster(x2, y2)
        if c1 == c2:
            # 同じクラスタを隔てている壁は壊さない
            return
        clusterling(c1, c2)
        if x1 == x2:
            # 縦(下側)の壁を壊す
            maze[y1 * 2 + 2][x1 * 2 + 1] = ' '
        else:
            # 横(右側)の壁を壊す
            maze[y1 * 2 + 1][x1 * 2 + 2] = ' '

    def make():
        walls = []
        for y in range(height):
            for x in range(width):
                maze[y * 2 + 1][x * 2 + 1] = ' '
                y > 0 and walls.append((x, y - 1, x, y))  # 上側の壁とこの壁
                x > 0 and walls.append((x - 1, y, x, y))  # 左側の壁とこの壁
        random.shuffle(walls)
        for wall in walls:
            remove(wall)

    make()
    maze[-2][1] = 'S'
    maze[1][-2] = 'G'
    return maze


def main():
    height, width = 10, 20
    if len(sys.argv) == 2:
        height = width = int(sys.argv[1])
    elif len(sys.argv) == 3:
        height, width = map(int, sys.argv[1:])
    show_maze(maze(height, width))

if __name__ == '__main__':
    main()