Python: Closest Palindrome number of a given integer

Last update on April 17 2025 13:05:05 (UTC/GMT +8 hours)

Closest Palindrome Number

Write a Python program to find the closest palindrome number to a given integer. If there are two palindrome numbers in absolute distance return the smaller number.

Sample Solution-1:

Python Code:

# Define a function 'test' that finds the closest palindrome number to the given integer 'n'.
def test(n):
    # Initialize two variables 'x' and 'y' to the original value of 'n'.
    x = n
    y = n
    
    # Loop indefinitely until a palindrome is found.
    while True:
        # Check if the string representation of 'x' is a palindrome.
        if str(x) == str(x)[::-1]:
            # If 'x' is a palindrome, return it as the closest palindrome.
            return x
        
        # Decrement 'x' by 1 for the next iteration.
        x -= 1
        
        # Check if the string representation of 'y' is a palindrome.
        if str(y) == str(y)[::-1]:
            # If 'y' is a palindrome, return it as the closest palindrome.
            return y
        
        # Increment 'y' by 1 for the next iteration.
        y += 1

# Test case 1
n1 = 120
print("Original number: ", n1)
print("Closest Palindrome number of the said number: ", test(n1))

# Test case 2
n2 = 321
print("\nOriginal number: ", n2)
print("Closest Palindrome number of the said number: ", test(n2))

# Test case 3
n3 = 43
print("\nOriginal number: ", n3)
print("Closest Palindrome number of the said number: ", test(n3))

# Test case 4
n4 = 1234
print("\nOriginal number: ", n4)
print("Closest Palindrome number of the said number: ", test(n4))

Sample Output:

Original number:  120
Closest Palindrome number of the said number:  121
Original number:  321
Closest Palindrome number of the said number:  323
Original number:  43
Closest Palindrome number of the said number:  44
Original number:  1234
Closest Palindrome number of the said number:  1221

Explanation:

Here is a breakdown of the above Python code:

test Function:

The "test()" function takes an integer 'n' as input.
It initializes two variables 'x' and 'y' to the original value of 'n'.
The function then enters an infinite loop, decrementing 'x' and incrementing 'y' in each iteration.
If a palindrome is found during this process, it is returned as the closest palindrome.

Flowchart:

Sample Solution-2:

Python Code:

# Define a function 'test' that finds the closest palindrome number to the given integer 'n'.
def test(n):
    # Initialize a variable 'result' to 0.
    result = 0
    
    # Loop until a palindrome is found.
    while n:
        # Check if the string representation of 'n - result' is a palindrome.
        if str(n - result) == str(n - result)[::-1]:
            # If true, return 'n - result' as the closest palindrome.
            return n - result
        # Check if the string representation of 'n + result' is a palindrome.
        elif str(n + result) == str(n + result)[::-1]:
            # If true, return 'n + result' as the closest palindrome.
            return n + result
        
        # Increment 'result' for the next iteration.
        result += 1

# Test case 1
n1 = 120
print("Original number: ", n1)
print("Closest Palindrome number of the said number: ", test(n1))

# Test case 2
n2 = 321
print("\nOriginal number: ", n2)
print("Closest Palindrome number of the said number: ", test(n2))

# Test case 3
n3 = 43
print("\nOriginal number: ", n3)
print("Closest Palindrome number of the said number: ", test(n3))

# Test case 4
n4 = 1234
print("\nOriginal number: ", n4)
print("Closest Palindrome number of the said number: ", test(n4))

Sample Output:

Original number:  120
Closest Palindrome number of the said number:  121
Original number:  321
Closest Palindrome number of the said number:  323
Original number:  43
Closest Palindrome number of the said number:  44
Original number:  1234
Closest Palindrome number of the said number:  1221

Explanation:

Here is a breakdown of the above Python code:

test Function:

The "test()" function takes an integer 'n' as input.
It initializes a variable result to 0.
The function enters a loop until a palindrome is found:

It checks if n - result or n + result is a palindrome.
If true, it returns the corresponding value as the closest palindrome.

Flowchart:

For more Practice: Solve these Related Problems:

Write a Python program to find the palindrome number closest to a given integer by searching both upward and downward.
Write a Python program to determine the nearest palindrome to an integer, returning the smaller one if two are equidistant.
Write a Python program to compute the absolute differences between a number and nearby palindromes to find the closest match.
Write a Python program to iterate outward from a given number until a palindrome is found, then return that palindrome.

Go to:

Previous: Write a Python program to reverse the binary representation of an given integer and convert the reversed binary number into an integer.
Next: Write a Python program to convert all items in a given list to float values.

Python Code Editor:

Have another way to solve this solution? Contribute your code (and comments) through Disqus.