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reverse_integer.py
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reverse_integer.py
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# https://leetcode.com/problems/reverse-integer/
#Reverse digits of an integer.
# Example1: x = 123, return 321
# Example2: x = -123, return -321
# Looks like l33tcode has this solution implemented for Java/ C , Note that
# the system max in those languages have a different range
# Thinking about this again , I guess I might have taken a short cut here .
# I shouldn't have used string reverse here , and should have used a multiply logic.
import unittest
import sys
import math
class Solution:
# @return an integer
def reverse(self, x):
isNegative = False
new_sysmax = int(math.pow(2,31)-1)
new_sysmin = new_sysmax*-1
if x < 0 :
rev_int = int(str(abs(x))[::-1])*-1
if rev_int < new_sysmin:
return 0
else:
return rev_int
else:
rev_int = int(str(abs(x))[::-1])
if rev_int < new_sysmax:
return rev_int
else:
return 0
class TestReverseInteger(unittest.TestCase):
my_solution = Solution()
def test_reverse_positive_integer(self):
self.assertEqual(self.my_solution.reverse(123),321)
def test_reverse_negative_integer(self):
self.assertEqual(self.my_solution.reverse(-123),-321)
def test_reverse_zero(self):
self.assertEqual(self.my_solution.reverse(0),0)
def test_overflow_max(self):
self.assertEqual(self.my_solution.reverse(9463847412),0)
# the reversed interger overflows the Maximum
if __name__ == "__main__":
unittest.main()