matrix_walker.py

# coding: utf-8

from pprint import pprint

RIGHT, DOWN, LEFT, UP = 1, 2, 3, 4

class MatrixWalker(object):
    def __init__(self, width):
        self.width = width
        x = width + 2   # 多一圈，作为最外圈的墙壁
        self.matrix = []
        for i in xrange(x):
            line = []
            for j in xrange(x):
                line.append(None)
            self.matrix.append(line)
        self.matrix[0] = [0] * x
        self.matrix[-1] = [0] * x
        for line in self.matrix:
            line[0] = 0
            line[-1] = 0
        self.x = 1   # 初始位置
        self.y = 1
        self.dire = RIGHT   # 初始方向
        self.count = 1   # 走过的步数

    def show(self):
        pprint(self.matrix)

    def turn_direction(self):
        '''撞到墙壁时转换方向，固定→↓←↑的顺序
        '''
        self.dire = self.dire+1 if self.dire<4 else 1

    def peek_next(self):
        '''查看下一步位置的状态
        '''
        return {
                RIGHT: self.matrix[self.y][self.x+1],
                DOWN: self.matrix[self.y+1][self.x],
                LEFT: self.matrix[self.y][self.x-1],
                UP: self.matrix[self.y-1][self.x],
            }[self.dire]

    def go_next(self):
        '''走到下一步
        '''
        self.count += 1
        if self.dire == RIGHT:
            self.x += 1
        elif self.dire == DOWN:
            self.y += 1
        elif self.dire == LEFT:
            self.x -= 1
        elif self.dire == UP:
            self.y -= 1

    def walk(self):
        '''递归遍历矩阵，太宽时有可能会达到最深函数调用层数
        '''
        if self.count > self.width * self.width:
            return
        self.matrix[self.y][self.x] = self.count
        if self.peek_next() is not None:
            self.turn_direction()
        self.go_next()
        return self.walk()


if __name__ == '__main__':
    m = MatrixWalker(5)
    m.walk()
    m.show()