Create prime-palindrome.py

Author: kamyu104

Python/prime-palindrome.py

@@ -0,0 +1,54 @@
+# Time:  O(n^(3/2))
+# Space: O(logn)
+
+# Find the smallest prime palindrome greater than or equal to N.
+# Recall that a number is prime if it's only divisors are 1 and itself,
+# and it is greater than 1.
+#
+# For example, 2,3,5,7,11 and 13 are primes.
+#
+# Recall that a number is a palindrome if it reads the same from
+# left to right as it does from right to left.
+#
+# For example, 12321 is a palindrome.
+#
+# Example 1:
+#
+# Input: 6
+# Output: 7
+# Example 2:
+#
+# Input: 8
+# Output: 11
+# Example 3:
+#
+# Input: 13
+# Output: 101
+#
+# Note:
+# - 1 <= N <= 10^8
+# - The answer is guaranteed to exist and be less than 2 * 10^8.
+
+try:
+    xrange          # Python 2
+except NameError:
+    xrange = range  # Python 3
+
+
+class Solution(object):
+    def primePalindrome(self, N):
+        """
+        :type N: int
+        :rtype: int
+        """
+        def is_prime(n):
+            if n < 2 or n % 2 == 0:
+                return n == 2
+            return all(n % d for d in xrange(3, int(n**.5) + 1, 2))
+
+        if 8 <= N <= 11:
+            return 11
+        for i in xrange(10**(len(str(N))//2), 10**5):
+            j = int(str(i) + str(i)[-2::-1])
+            if j >= N and is_prime(j):
+                return j