- #刷题
Recursion题目求解
kakachelsea14905
最近在自学CS61A(python)，做homework3的时候遇到一道题，想了半天也解决不了，希望大家帮忙想个算法。。。谢谢！
题目的关键是不能有任何assignment语句，也就是要用recursion，可我想不出做法。
题目如下：
Write a function that takes a positive integer n and returns the number of ten-pairs it contains. A ten-pair is a pairs of digits within n that sum to 10. Do not use any assignment statements.The number 7,823,952 has 3 ten-pairs. The first and fourth digits sum to 7+3=10, the second and third digits sum to 8+2=10, and the second and last digit sum to 8+2=10:
def ten_pairs(n): """Return the number of ten-pairs within positive integer n.
>>> ten_pairs(7823952)
3
>>> ten_pairs(55055)
6
>>> ten_pairs(9641469)
6
"""
题目的关键是不能有任何assignment语句，也就是要用recursion，可我想不出做法。
题目如下：
Write a function that takes a positive integer n and returns the number of ten-pairs it contains. A ten-pair is a pairs of digits within n that sum to 10. Do not use any assignment statements.The number 7,823,952 has 3 ten-pairs. The first and fourth digits sum to 7+3=10, the second and third digits sum to 8+2=10, and the second and last digit sum to 8+2=10:
def ten_pairs(n): """Return the number of ten-pairs within positive integer n.
>>> ten_pairs(7823952)
3
>>> ten_pairs(55055)
6
>>> ten_pairs(9641469)
6
"""
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