Create find-the-closest-palindrome.py

Author: kamyu104

Python/find-the-closest-palindrome.py

@@ -0,0 +1,27 @@
+# Time:  O(l)
+# Space: O(l)
+
+# Given an integer n, find the closest integer (not including itself), which is a palindrome.
+#
+# The 'closest' is defined as absolute difference minimized between two integers.
+#
+# Example 1:
+# Input: "123"
+# Output: "121"
+# Note:
+# The input n is a positive integer represented by string, whose length will not exceed 18.
+# If there is a tie, return the smaller one as answer.
+
+class Solution(object):
+    def nearestPalindromic(self, n):
+        """
+        :type n: str
+        :rtype: str
+        """
+        l = len(n)
+        candidates = set((str(10**l + 1), str(10**(l - 1) - 1)))
+        prefix = int(n[:(l + 1)/2])
+        for i in map(str, (prefix-1, prefix, prefix+1)):
+            candidates.add(i + [i, i[:-1]][l%2][::-1])
+        candidates.discard(n)
+        return min(candidates, key=lambda x: (abs(int(x) - int(n)), int(x)))