알고리즘/LeetCode
2396. Strictly Palindromic Number
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2022. 12. 23. 12:24
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문제)
2396. Strictly Palindromic Number
An integer n is strictly palindromic if, for every base b between 2 and n - 2 (inclusive), the string representation of the integer n in base b is palindromic.
Given an integer n, return true if n is strictly palindromic and false otherwise.
A string is palindromic if it reads the same forward and backward.
Example 1:
Input: n = 9
Output: false
Explanation: In base 2: 9 = 1001 (base 2), which is palindromic.
In base 3: 9 = 100 (base 3), which is not palindromic.
Therefore, 9 is not strictly palindromic so we return false.
Note that in bases 4, 5, 6, and 7, n = 9 is also not palindromic.
Example 2:
Input: n = 4
Output: false
Explanation: We only consider base 2: 4 = 100 (base 2), which is not palindromic.
Therefore, we return false.
Constraints:
- 4 <= n <= 105
솔루션1)
- 2부터 n-2까지 반복하면서 진수변환해서 palindrome를 체크
class Solution:
def isStrictlyPalindromic(self, n: int) -> bool:
for i in range(2, n-1):
val = self.convert_to_base_n(n, i)
if val != val[::-1]:
return False
return True
def convert_to_base_n(self, num, n):
ret = []
while num:
num, remainder = divmod(num, n)
ret.append(str(remainder))
return ''.join(ret.reverse())
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