866.md

[866] Prime Palindrome

Description

link

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Solution

• See Code

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Code

O(n)

class Solution:
    def primePalindrome(self, N: int) -> int:
        def isPrime(x):
            if x < 2 or x % 2 == 0: return x == 2
            for i in range(3, int(x**0.5) + 1, 2):
                if x % i == 0: return False
            return True
        if 8 <= N <= 11: return 11
        for x in range(10 ** (len(str(N)) // 2), 10**5):
            y = int(str(x) + str(x)[-2::-1])
            if y >= N and isPrime(y): return y