题目:地上有一个m行和n列的方格。一个机器人从坐标0,0的格子开始移动,每一次只能向左,右,上,下四个方向移动一格,但是不能进入行坐标和列坐标的数位之和大于k的格子。 例如,当k为18时,机器人能够进入方格(35,37),因为3+5+3+7 = 18。但是,它不能进入方格(35,38),因为3+5+3+8 = 19。请问该机器人能够达到多少个格子?
代码(一):
# -*- coding:utf-8 -*-
class Solution:
def movingCount(self, threshold, rows, cols):
# write code here
if threshold < 0 or rows <= 0 or cols <= 0:
return 0
marked = [[False for r in range(cols)] for r in range(rows)]
count = self.find_path(threshold,0,0,rows,cols,marked)
return count
def find_path(self,threshold,row,col,rows,cols,marked):
count = 0
if self.check(threshold,row,col,rows,cols,marked)and not marked[row][col]:
marked[row][col] = True
count = 1 + self.find_path(threshold,row+1,col,rows,cols,marked)+self.find_path(threshold,row,col+1,rows,cols,marked)
return count
def check(self,threshold,row,col,rows,cols,marked):
sum_ = sum([int(i) for i in str(row)]) + sum([int(i) for i in str(col)])
if row<0 or col < 0 or row >= rows or col >=cols or sum_>threshold:
return False
else:
return True
代码思路:回溯法。
递归