'''

Palindrome Integer

Determine whether an integer is a palindrome.

An integer is a palindrome when it reads the same backward as forward.

Input: 121

Output: True

Input: -121

Output: False

Output explanation: From left to right, it reads -121. From right to left, it becomes 121-. Therefore it is not a palindrome.

Input: 10

Output: false

Output oxplanation: Reads 01 from right to left. Therefore it is not a palindrome.

=========================================

Juste reverse the number and compare it with the original.

Time Complexity: O(N) , N = number of digits

Space Complexity: O(1)

If you care about integer overflow (in Python you shouldn't care about this), then reverse only a half of the number

and compare it with the other half. Also this solution is faster than the previous one because iterates only a half of the number.

Time Complexity: O(N)

Space Complexity: O(1)

'''

##############

# Solution 1 #

##############

def palindrome_integer_1(x):

if x < 0:

return False

rev = 0

temp = x

while temp > 0:

rev = (rev * 10) + (temp % 10)

temp //= 10

return rev == x

##############

# Solution 2 #

##############

def palindrome_integer_2(x):

# check if negative or ends with zero

if (x < 0) or (x > 0 and x % 10 == 0):

return False

rev = 0

# if the reversed number is bigger from the original

# that means the reversed number has same number of digits or more (1 or 2 more)

while x > rev:

rev = (rev * 10) + (x % 10)

x //= 10

# first comparison is for even number of digits and the second for odd number of digits

return (rev == x) or (rev // 10 == x)

###########

# Testing #

###########

# Test 1

# Correct result => True

x = 121

print(palindrome_integer_1(x))

print(palindrome_integer_2(x))

# Test 2

# Correct result => False

x = -121

print(palindrome_integer_1(x))

print(palindrome_integer_2(x))

# Test 2

# Correct result => False

x = 10

print(palindrome_integer_1(x))

print(palindrome_integer_2(x))