integer_reverse.py

# LeetCode #7. Reverse Integer
#
# Given a signed 32-bit integer x, return x with its digits reversed. If reversing x causes the value to go outside the signed 32-bit integer range [-2^31, 2^31 - 1], then return 0.
#
# Assume the environment does not allow you to store 64-bit integers (signed or unsigned).
#
# Example 1:
#     Input: x = 123
#     Output: 321
# Example 2:
#     Input: x = -123
#     Output: -321
# Example 3:
#     Input: x = 120
#     Output: 21
#
# Constraints:
#     -2^31 <= x <= 2^31 - 1


def reverse(x :int) -> int :
    tmpnum = 0
    tmpx = abs(x)
    while tmpx > 0 :
        tmpnum = (tmpnum * 10) + tmpx%10
        tmpx = tmpx//10
    if not (-2**31 < x < 2**31 - 1 ) :
        return 0
    return -(tmpnum) if x < 0 else tmpnum

test_ints = [
    123,
    100,
    -456,
    0,
    987654321,
    1000000002,
    1000000000000002,
]

for i in test_ints :
    print(f'input : {i}, output : {reverse(i)}')