题目
You are given two arrays with positive integers arr1 and arr2.
A prefix of a positive integer is an integer formed by one or more of its digits, starting from its leftmost digit. For example, 123 is a prefix of the integer 12345, while 234 is not.
A common prefix of two integers a and b is an integer c, such that c is a prefix of both a and b. For example, 5655359 and 56554 have a common prefix 565 while 1223 and 43456 do not have a common prefix.
You need to find the length of the longest common prefix between all pairs of integers (x, y) such that x belongs to arr1 and y belongs to arr2.
Return the length of the longest common prefix among all pairs. If no common prefix exists among them, return 0.
解题思路
把第一个数组的所有前缀放到一个数组里，求前缀可以对数字//10
之后遍历所有第二个数组里的数，求出所有前缀，如果出现在set里，就更新结果
代码
class Solution:
def longestCommonPrefix(self, arr1: List[int], arr2: List[int]) -> int:
prefix = set()
res = 0
for n in arr1:
while n:
prefix.add(n)
n //= 10
for n in arr2:
while n:
if n in prefix:
res = max(res, len(str(n)))
break
n //= 10
return res
