剑指Offer66-机器人的运动范围（记忆）

# -*- coding:utf-8 -*-
class Solution:
    def __init__(self):
        self.count = 0
    def movingCount(self, threshold, rows, cols):
        # write code here
        def helper(i, j):
            if i<0 or i>=rows or j<0 or j>=cols:
                return
            tmpi = [int(item) for item in str(i)]
            tmpj = [int(item) for item in str(j)]
            if sum(tmpi) + sum(tmpj) > threshold or visited[i][j] != 0:
                return
                
            # 如果能执行到这一步说明和<=k，且之前未访问过
            visited[i][j] = 1
            self.count += 1
            helper(i+1, j)
            helper(i-1, j)
            helper(i, j+1)
            helper(i, j-1)
            
        visited = [[0 for i in range(cols)] for j in range(rows)]
        # 未访问过的为0，访问过的为1
        helper(0, 0)
        return self.count