剑指Offer(Python多种思路实现):机器人的运动范围
面试13题：
题目：机器人的运动范围
题：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？
解题思路一：回溯法、递归
class Solution:
def movingCount(self, threshold, rows, cols):
# write code here
if threshold<0 or rows<1 or cols<1:
return 0
markmatrix=[False]*(rows*cols)
count=self.movingCountCore(threshold,rows,cols,0,0,markmatrix)
return count
def movingCountCore(self,threshold,rows,cols,row,col,markmatrix):
value=0
if self.check(threshold,rows,cols,row,col,markmatrix):
markmatrix[row*cols+col]=True
value = 1+ self.movingCountCore(threshold, rows, cols, row-1, col, markmatrix)+ \
self.movingCountCore(threshold, rows, cols, row+1, col, markmatrix) + \
self.movingCountCore(threshold, rows, cols, row, col-1, markmatrix) + \
self.movingCountCore(threshold, rows, cols, row, col+1, markmatrix)
return value
def check(self,threshold,rows,cols,row,col,markmatrix):
if row >= 0 and row < rows and col >= 0 and col < cols and \
self.getDigitNum(row)+self.getDigitNum(col)<=threshold and not markmatrix[row*cols+col]:
return True
return False
def getDigitNum(self,number):
sum=0
while(number>0):
sum+=number%10
number=number//10
return sum解题思路一：回溯法、递归
def movingCount(self, threshold, rows, cols):
visited = [[False]*cols for _ in range(rows)]
def getSum(x, y):
return sum(map(int, str(x)+str(y)))
def movingCore(threshold, rows, cols, row, col):
if getSum(row, col) <= threshold:
visited[row][col] = True
for x, y in ((row-1, j), (i+1, j), (i, j-1), (i, j+1)):
if 0<=x<rows and 0<=y<cols and not visited[x][y]:
movingCore(threshold, rows, cols, x, y)
movingCore(threshold, rows, cols, 0, 0)
return sum(sum(visited, []))