Check Palindrome number using Recursion in R

R Programming: Control Structure Exercise-19 with Solution

Write a R program function to check if a given number is a palindrome using recursion.

Sample Solution :

R Programming Code :

# Define a function to check if a given number is a palindrome using recursion
is_palindrome <- function(number) {
    # Convert the number to a character string
    num_str <- as.character(number)
    
    # Define a helper function to check if a string is a palindrome
    is_palindrome_helper <- function(str) {
        if (nchar(str) <= 1) {
            return(TRUE)  # Base case: Single character or empty string is a palindrome
        } else {
            first_char <- substr(str, 1, 1)  # Get the first character
            last_char <- substr(str, nchar(str), nchar(str))  # Get the last character
            
            # Check if the first and last characters are equal
            if (first_char != last_char) {
                return(FALSE)  # If not equal, not a palindrome
            } else {
                # Recursively check the substring without the first and last characters
                return(is_palindrome_helper(substr(str, 2, nchar(str) - 1)))
            }
        }
    }
    
    # Call the helper function with the number converted to a string
    return(is_palindrome_helper(num_str))
}

# Test the function with example inputs
number1 <- 42324
number2 <- 1234

# Check if the numbers are palindromes and print the result
cat("Number", number1, "is a palindrome!", is_palindrome(number1), "\n")
cat("Number", number2, "is a palindrome!", is_palindrome(number2), "\n")

Output:

Number 42324 is a palindrome! TRUE 
Number 1234 is a palindrome! FALSE    

Explatnaion:

In the exercise above,

• The "is_palindrome()" function takes a number as input and checks if it's a palindrome.
• Inside the function, the number is converted to a character string using 'as.character'.
• A helper function "is_palindrome_helper()" is defined to check if a string is a palindrome recursively.
• In the helper function, the base case is when the length of the string is 1 or less, in which case it returns 'TRUE'.
• Otherwise, it checks if the first and last characters of the string are equal. If they are, it recursively checks the substring without the first and last characters.
• The "is_palindrome()" function is called with the number converted to a string, and the result is returned.

R Programming Code Editor:

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