Create count-symmetric-integers.py

Author: kamyu104

Python/count-symmetric-integers.py

@@ -0,0 +1,23 @@
+# Time:  O(rlogr)
+# Space: O(r)
+
+# brute force, memoization
+MAX_R = 10**4
+LOOKUP = [-1]*MAX_R
+class Solution(object):
+    def countSymmetricIntegers(self, low, high):
+        """
+        :type low: int
+        :type high: int
+        :rtype: int
+        """
+        def check(x):
+            if LOOKUP[x-1] == -1:
+                digits = map(int, str(x))
+                if len(digits)%2:
+                    LOOKUP[x-1] = 0
+                else:
+                    LOOKUP[x-1] = int(sum(digits[i] for i in xrange(len(digits)//2)) == sum(digits[i] for i in xrange(len(digits)//2, len(digits))))
+            return LOOKUP[x-1]
+
+        return sum(check(x) for x in xrange(low, high+1))