从右边开始寻找整数的第k位
从右边开始寻找整数的第k位
Implement match_k, which takes in an integer k and returns a function that takes in a variable x and returns True if all the digits in x that are k apart are the same.
For example, match_k(2) returns a one argument function that takes in x and checks if digits that are 2 away in x are the same.
match_k(2)(1010) has the value of x = 1010 and digits 1, 0, 1, 0 going from left to right. 1 == 1 and 0 == 0, so the match_k(2)(1010) results in True.
match_k(2)(2010) has the value of x = 2010 and digits 2, 0, 1, 0 going from left to right. 2 != 1 and 0 == 0, so the match_k(2)(2010) results in False.
Important: You may not use strings or indexing for this problem.
Floor dividing by powers of 10 gets rid of the rightmost digits.
def match_k(k):
"""Returns a function that checks if digits k apart match.
>>> match_k(2)(1010)
True
>>> match_k(2)(2010)
False
>>> match_k(1)(1010)
False
>>> match_k(1)(1)
True
>>> match_k(1)(2111111111111111)
False
>>> match_k(3)(123123)
True
>>> match_k(2)(123123)
False
"""
def check(x):
while x // (10 ** k) > 0:
if (x % 10) != (x // (10 ** k)) % 10:
return False
x //= 10
return True
return check
分析：
- 判断最后一位与右边数第k位数字是否相同：
(x % 10) != (x // (10 ** k)) % 10 - 如果不相同，则这个数肯定不符合题目要求，直接返回
False - 如果相同，则将比较位置转为左手边的下一个数字：
x //= 10
