Python Challenges: Reverse the digits of an integer

Last update on December 21 2024 07:49:29 (UTC/GMT +8 hours)

Write a Python program to reverse the digits of an integer.

Explanation:

Sample Example:

Input : 234
Input : -234
Output: 432
Output : -432

Sample Solution-1:

Python Code:

def reverse_integer(x):
        sign = -1 if x < 0 else 1
        x *= sign

        # Remove leading zero in the reversed integer
        while x:
            if x % 10 == 0:
                x /= 10
            else:
                break

        # string manipulation
        x = str(x)
        lst = list(x)  # list('234') returns ['2', '3', '4']
        lst.reverse()
        x = "".join(lst)
        x = int(x)
        return sign*x
    
print(reverse_integer(234))
print(reverse_integer(-234))

Sample Output:

432   
-432

Flowchart:

Sample Solution-2:

Reverses a number:

• Use str() to convert the number to a string, slice notation to reverse it and str.replace() to remove the sign.
• Use float() to convert the result to a number and math.copysign() to copy the original sign.

Python Code:

from math import copysign
def reverse_number(n):
  return copysign(float(str(n)[::-1].replace('-', '')), n) 
print(reverse_number(873))
print(reverse_number(-900))
print(reverse_number(234.6))
print(reverse_number(-15.78))

Sample Output:

378.0
-9.0
6.432
-87.51

Flowchart:

Python Code Editor:

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