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Print all palindromes in a given range

The problem is to find and print all palindrome numbers within a given range. A palindrome number is a number that remains the same when its digits are reversed. For example, 121 and 454 are palindrome numbers because their digits remain the same when reversed.

Problem Statement and Example

Given a range [s, e] (inclusive), the task is to find and print all palindrome numbers in that range. For instance, if the range is [50, 300], the output should be:

Palindromes in range (50 300) is
    55 66 77
    88 99 101
    111 121 131
    141 151 161
    171 181 191
    202 212 222
    232 242 252
    262 272 282
    292

Similarly, for the range [1000, 1200], the output should be:

Palindromes in range (1000 1200) is
    1001 1111

Pseudocode

function reverse(number):
    result = 0
    while number > 0:
        result = (result * 10) + (number % 10)
        number = number / 10
    return result

function palindromesInRange(s, e):
    if s < 0 or e < 0:
        return
    count = 0
    print "Palindromes in range (" + s + " " + e + ") is"
    for i from s to e - 1:
        if reverse(i) == i:
            count = count + 1
            print i
            if count % 3 == 0:
                print new line
    if count == 0:
        print "None"

main:
    palindromesInRange(50, 300)
    palindromesInRange(1000, 1200)

Algorithm Explanation

  1. The reverse function takes an integer number as input and returns its reversal view. It initializes a variable result to 0. Then, it iterates through each digit of the number using a while loop and appends each digit to result in a reversed manner.

  2. The palindromesInRange function takes two integers s and e as input, representing the lower and upper bounds of the range, respectively. It first checks if either s or e is negative, in which case it returns immediately as the input range is invalid.

  3. It initializes a variable count to 0, which will be used to track the number of palindrome numbers found within the range.

  4. The function then prints the header with the given range.

  5. It iterates through each number i in the given range from s to e-1.

  6. For each number i, it checks if reverse(i) == i. If this condition is true, it means i is a palindrome number, and it is printed.

  7. The count variable is incremented, and if the count becomes a multiple of 3, a new line is added to format the output.

  8. After the loop, if no palindrome numbers were found (count == 0), it prints "None."

Code Solution

Here given code implementation process.

/*
    C program for
    Print all palindromes in a given range
*/
#include <stdio.h>

// Returns the Reversal view of given number
int reverse(int number)
{
	int result = 0;
	while (number > 0)
	{
		// Append digit
		result = (result *10) + (number % 10);
		//remove last digit
		number /= 10;
	}
	return result;
}
// Handles the request of display all palindrome in given range
void palindromesInRange(int s, int e)
{
	if (s < 0 || e < 0)
	{
		return;
	}
	int count = 0;
	printf("\n Palindromes in range (%d %d) is \n", s, e);
	// Execute loop in given range
	for (int i = s; i < e; ++i)
	{
		if (reverse(i) == i)
		{
			count++;
			printf(" %d", i);
			if (count % 3 == 0)
			{
				printf("\n");
			}
		}
	}
	if (count == 0)
	{
		printf("\n None");
	}
}
int main(int argc, char
	const *argv[])
{
	// Test
	palindromesInRange(50, 300);
	palindromesInRange(1000, 1200);
	return 0;
}

Output

 Palindromes in range (50 300) is
 55 66 77
 88 99 101
 111 121 131
 141 151 161
 171 181 191
 202 212 222
 232 242 252
 262 272 282
 292
 Palindromes in range (1000 1200) is
 1001 1111

/*
    Java program for
    Print all palindromes in a given range
*/
public class Palindrome
{
    // Returns the Reversal view of given number
    public int reverse(int number)
    {
        int result = 0;
        while (number > 0)
        {
            // Append digit
            result = (result * 10) + (number % 10);
            //remove last digit
            number /= 10;
        }
        return result;
    }
    // Handles the request of display all palindrome in given range
    public void palindromesInRange(int s, int e)
    {
        if (s < 0 || e < 0)
        {
            return;
        }
        int count = 0;
        System.out.print("\n Palindromes in range (" + s + " " + e + ") is \n");
        // Execute loop in given range
        for (int i = s; i < e; ++i)
        {
            if (reverse(i) == i)
            {
                count++;
                System.out.print(" " + i );
                if (count % 3 == 0)
                {
                    System.out.print("\n");
                }
            }
        }
        if (count == 0)
        {
            System.out.print("\n None");
        }
    }
    public static void main(String[] args)
    {
        Palindrome task = new Palindrome();
        // Test
        task.palindromesInRange(50, 300);
        task.palindromesInRange(1000, 1200);
    }
}

Output

 Palindromes in range (50 300) is
 55 66 77
 88 99 101
 111 121 131
 141 151 161
 171 181 191
 202 212 222
 232 242 252
 262 272 282
 292
 Palindromes in range (1000 1200) is
 1001 1111
// Include header file
#include <iostream>
using namespace std;
/*
    C++ program for
    Print all palindromes in a given range
*/
class Palindrome
{
	public:
		// Returns the Reversal view of given number
		int reverse(int number)
		{
			int result = 0;
			while (number > 0)
			{
				// Append digit
				result = (result *10) + (number % 10);
				//remove last digit
				number /= 10;
			}
			return result;
		}
	// Handles the request of display all palindrome in given range
	void palindromesInRange(int s, int e)
	{
		if (s < 0 || e < 0)
		{
			return;
		}
		int count = 0;
		cout << "\n Palindromes in range (" << s << " " << e << ") is \n";
		// Execute loop in given range
		for (int i = s; i < e; ++i)
		{
			if (this->reverse(i) == i)
			{
				count++;
				cout << " " << i;
				if (count % 3 == 0)
				{
					cout << "\n";
				}
			}
		}
		if (count == 0)
		{
			cout << "\n None";
		}
	}
};
int main()
{
	Palindrome *task = new Palindrome();
	// Test
	task->palindromesInRange(50, 300);
	task->palindromesInRange(1000, 1200);
	return 0;
}

Output

 Palindromes in range (50 300) is
 55 66 77
 88 99 101
 111 121 131
 141 151 161
 171 181 191
 202 212 222
 232 242 252
 262 272 282
 292
 Palindromes in range (1000 1200) is
 1001 1111
// Include namespace system
using System;
/*
    Csharp program for
    Print all palindromes in a given range
*/
public class Palindrome
{
	// Returns the Reversal view of given number
	public int reverse(int number)
	{
		int result = 0;
		while (number > 0)
		{
			// Append digit
			result = (result * 10) + (number % 10);
			//remove last digit
			number /= 10;
		}
		return result;
	}
	// Handles the request of display all palindrome in given range
	public void palindromesInRange(int s, int e)
	{
		if (s < 0 || e < 0)
		{
			return;
		}
		int count = 0;
		Console.Write("\n Palindromes in range (" + s + " " + e + ") is \n");
		// Execute loop in given range
		for (int i = s; i < e; ++i)
		{
			if (this.reverse(i) == i)
			{
				count++;
				Console.Write(" " + i);
				if (count % 3 == 0)
				{
					Console.Write("\n");
				}
			}
		}
		if (count == 0)
		{
			Console.Write("\n None");
		}
	}
	public static void Main(String[] args)
	{
		Palindrome task = new Palindrome();
		// Test
		task.palindromesInRange(50, 300);
		task.palindromesInRange(1000, 1200);
	}
}

Output

 Palindromes in range (50 300) is
 55 66 77
 88 99 101
 111 121 131
 141 151 161
 171 181 191
 202 212 222
 232 242 252
 262 272 282
 292
 Palindromes in range (1000 1200) is
 1001 1111
package main
import "fmt"
/*
    Go program for
    Print all palindromes in a given range
*/

// Returns the Reversal view of given number
func reverse(number int) int {
	var result int = 0
	for (number > 0) {
		// Append digit
		result = (result * 10) + (number % 10)
		//remove last digit
		number = number / 10
	}
	return result
}
// Handles the request of display all palindrome in given range
func palindromesInRange(s, e int) {
	if s < 0 || e < 0 {
		return
	}
	var count int = 0
	fmt.Print("\n Palindromes in range (", s, " ", e, ") is \n")
	// Execute loop in given range
	for i := s ; i < e ; i++ {
		if reverse(i) == i {
			count++
			fmt.Print(" ", i)
			if count % 3 == 0 {
				fmt.Print("\n")
			}
		}
	}
	if count == 0 {
		fmt.Print("\n None")
	}
}
func main() {

	// Test
	palindromesInRange(50, 300)
	palindromesInRange(1000, 1200)
}

Output

 Palindromes in range (50 300) is
 55 66 77
 88 99 101
 111 121 131
 141 151 161
 171 181 191
 202 212 222
 232 242 252
 262 272 282
 292
 Palindromes in range (1000 1200) is
 1001 1111
<?php
/*
    Php program for
    Print all palindromes in a given range
*/
class Palindrome
{
	// Returns the Reversal view of given number
	public	function reverse($number)
	{
		$result = 0;
		while ($number > 0)
		{
			// Append digit
			$result = ($result * 10) + ($number % 10);
			//remove last digit
			$number = (int)($number / 10);
		}
		return $result;
	}
	// Handles the request of display all palindrome in given range
	public	function palindromesInRange($s, $e)
	{
		if ($s < 0 || $e < 0)
		{
			return;
		}
		$count = 0;
		echo("\n Palindromes in range (".$s." ".$e.") is \n");
		// Execute loop in given range
		for ($i = $s; $i < $e; ++$i)
		{
			if ($this->reverse($i) == $i)
			{
				$count++;
				echo(" ".$i);
				if ($count % 3 == 0)
				{
					echo("\n");
				}
			}
		}
		if ($count == 0)
		{
			echo("\n None");
		}
	}
}

function main()
{
	$task = new Palindrome();
	// Test
	$task->palindromesInRange(50, 300);
	$task->palindromesInRange(1000, 1200);
}
main();

Output

 Palindromes in range (50 300) is
 55 66 77
 88 99 101
 111 121 131
 141 151 161
 171 181 191
 202 212 222
 232 242 252
 262 272 282
 292
 Palindromes in range (1000 1200) is
 1001 1111
/*
    Node JS program for
    Print all palindromes in a given range
*/
class Palindrome
{
	// Returns the Reversal view of given number
	reverse(number)
	{
		var result = 0;
		while (number > 0)
		{
			// Append digit
			result = (result * 10) + (number % 10);
			//remove last digit
			number = parseInt(number / 10);
		}
		return result;
	}
	// Handles the request of display all palindrome in given range
	palindromesInRange(s, e)
	{
		if (s < 0 || e < 0)
		{
			return;
		}
		var count = 0;
		process.stdout.write("\n Palindromes in range (" + 
                             s + " " + e + ") is \n");
		// Execute loop in given range
		for (var i = s; i < e; ++i)
		{
			if (this.reverse(i) == i)
			{
				count++;
				process.stdout.write(" " + i);
				if (count % 3 == 0)
				{
					process.stdout.write("\n");
				}
			}
		}
		if (count == 0)
		{
			process.stdout.write("\n None");
		}
	}
}

function main()
{
	var task = new Palindrome();
	// Test
	task.palindromesInRange(50, 300);
	task.palindromesInRange(1000, 1200);
}
main();

Output

 Palindromes in range (50 300) is
 55 66 77
 88 99 101
 111 121 131
 141 151 161
 171 181 191
 202 212 222
 232 242 252
 262 272 282
 292
 Palindromes in range (1000 1200) is
 1001 1111
#    Python 3 program for
#    Print all palindromes in a given range
class Palindrome :
	#  Returns the Reversal view of given number
	def reverse(self, number) :
		result = 0
		while (number > 0) :
			#  Append digit
			result = (result * 10) + (number % 10)
			# remove last digit
			number = int(number / 10)
		
		return result
	
	#  Handles the request of display all palindrome in given range
	def palindromesInRange(self, s, e) :
		if (s < 0 or e < 0) :
			return
		
		count = 0
		print("\n Palindromes in range (", s ," ", e ,") is ")
		i = s
		#  Execute loop in given range
		while (i < e) :
			if (self.reverse(i) == i) :
				count += 1
				print(" ", i, end = "")
				if (count % 3 == 0) :
					print(end = "\n")
				
			
			i += 1
		
		if (count == 0) :
			print("\n None", end = "")
		
	

def main() :
	task = Palindrome()
	#  Test
	task.palindromesInRange(50, 300)
	task.palindromesInRange(1000, 1200)

if __name__ == "__main__": main()

Output

 Palindromes in range ( 50   300 ) is
  55  66  77
  88  99  101
  111  121  131
  141  151  161
  171  181  191
  202  212  222
  232  242  252
  262  272  282
  292
 Palindromes in range ( 1000   1200 ) is
  1001  1111
#    Ruby program for
#    Print all palindromes in a given range
class Palindrome 
	#  Returns the Reversal view of given number
	def reverse(number) 
		result = 0
		while (number > 0) 
			#  Append digit
			result = (result * 10) + (number % 10)
			# remove last digit
			number = number / 10
		end

		return result
	end

	#  Handles the request of display all palindrome in given range
	def palindromesInRange(s, e) 
		if (s < 0 || e < 0) 
			return
		end

		count = 0
		print("\n Palindromes in range (", s ," ", e ,") is \n")
		i = s
		#  Execute loop in given range
		while (i < e) 
			if (self.reverse(i) == i) 
				count += 1
				print(" ", i)
				if (count % 3 == 0) 
					print("\n")
				end

			end

			i += 1
		end

		if (count == 0) 
			print("\n None")
		end

	end

end

def main() 
	task = Palindrome.new()
	#  Test
	task.palindromesInRange(50, 300)
	task.palindromesInRange(1000, 1200)
end

main()

Output

 Palindromes in range (50 300) is 
 55 66 77
 88 99 101
 111 121 131
 141 151 161
 171 181 191
 202 212 222
 232 242 252
 262 272 282
 292
 Palindromes in range (1000 1200) is 
 1001 1111
/*
    Scala program for
    Print all palindromes in a given range
*/
class Palindrome()
{
	// Returns the Reversal view of given number
	def reverse(num: Int): Int = {
		var result: Int = 0;
      	var number = num;
		while (number > 0)
		{
			// Append digit
			result = (result * 10) + (number % 10);
			//remove last digit
			number = number / 10;
		}
		return result;
	}
	// Handles the request of display all palindrome in given range
	def palindromesInRange(s: Int, e: Int): Unit = {
		if (s < 0 || e < 0)
		{
			return;
		}
		var count: Int = 0;
		print("\n Palindromes in range (" + s + " " + e + ") is \n");
		var i: Int = s;
		// Execute loop in given range
		while (i < e)
		{
			if (reverse(i) == i)
			{
				count += 1;
				print(" " + i);
				if (count % 3 == 0)
				{
					print("\n");
				}
			}
			i += 1;
		}
		if (count == 0)
		{
			print("\n None");
		}
	}
}
object Main
{
	def main(args: Array[String]): Unit = {
		var task: Palindrome = new Palindrome();
		// Test
		task.palindromesInRange(50, 300);
		task.palindromesInRange(1000, 1200);
	}
}

Output

 Palindromes in range (50 300) is
 55 66 77
 88 99 101
 111 121 131
 141 151 161
 171 181 191
 202 212 222
 232 242 252
 262 272 282
 292
 Palindromes in range (1000 1200) is
 1001 1111
/*
    Swift 4 program for
    Print all palindromes in a given range
*/
class Palindrome
{
	// Returns the Reversal view of given number
	func reverse(_ num: Int) -> Int
	{
		var result: Int = 0;
        var number: Int = num;
		while (number > 0)
		{
			// Append digit
			result = (result * 10) + (number % 10);
			//remove last digit
			number = number / 10;
		}
		return result;
	}
	// Handles the request of display all palindrome in given range
	func palindromesInRange(_ s: Int, _ e: Int)
	{
		if (s < 0 || e < 0)
		{
			return;
		}
		var count: Int = 0;
		print("\n Palindromes in range (", s ," ", e ,") is ");
		var i: Int = s;
		// Execute loop in given range
		while (i < e)
		{
			if (self.reverse(i) == i)
			{
				count += 1;
				print(" ", i, terminator: "");
				if (count % 3 == 0)
				{
					print(terminator: "\n");
				}
			}
			i += 1;
		}
		if (count == 0)
		{
			print("\n None", terminator: "");
		}
	}
}
func main()
{
	let task: Palindrome = Palindrome();
	// Test
	task.palindromesInRange(50, 300);
	task.palindromesInRange(1000, 1200);
}
main();

Output

 Palindromes in range ( 50   300 ) is
  55  66  77
  88  99  101
  111  121  131
  141  151  161
  171  181  191
  202  212  222
  232  242  252
  262  272  282
  292
 Palindromes in range ( 1000   1200 ) is
  1001  1111
/*
    Kotlin program for
    Print all palindromes in a given range
*/
class Palindrome
{
	// Returns the Reversal view of given number
	fun reverse(num: Int): Int
	{
		var result: Int = 0;
      	var number: Int = num;
		while (number > 0)
		{
			// Append digit
			result = (result * 10) + (number % 10);
			//remove last digit
			number = number / 10;
		}
		return result;
	}
	// Handles the request of display all palindrome in given range
	fun palindromesInRange(s: Int, e: Int): Unit
	{
		if (s < 0 || e < 0)
		{
			return;
		}
		var count: Int = 0;
		print("\n Palindromes in range (" + s + " " + e + ") is \n");
		var i: Int = s;
		// Execute loop in given range
		while (i < e)
		{
			if (this.reverse(i) == i)
			{
				count += 1;
				print(" " + i);
				if (count % 3 == 0)
				{
					print("\n");
				}
			}
			i += 1;
		}
		if (count == 0)
		{
			print("\n None");
		}
	}
}
fun main(args: Array < String > ): Unit
{
	val task: Palindrome = Palindrome();
	// Test
	task.palindromesInRange(50, 300);
	task.palindromesInRange(1000, 1200);
}

Output

 Palindromes in range (50 300) is
 55 66 77
 88 99 101
 111 121 131
 141 151 161
 171 181 191
 202 212 222
 232 242 252
 262 272 282
 292
 Palindromes in range (1000 1200) is
 1001 1111

Resultant Output Explanation

The provided code executes the main function, which calls palindromesInRange twice with different ranges: palindromesInRange(50, 300) and palindromesInRange(1000, 1200).

  1. palindromesInRange(50, 300):

    • It finds and prints all palindrome numbers in the range [50, 300].
    • The output shows palindrome numbers in groups of three, separated by spaces. If there are fewer than three numbers in a group, the group ends early.
    • The output for this range is displayed as shown in the provided example.

  2. palindromesInRange(1000, 1200):

    • It finds and prints all palindrome numbers in the range [1000, 1200].
    • The output displays the palindrome numbers found in the given range.

Time Complexity

Let's analyze the time complexity of the code. For a given range [s, e], the palindromesInRange function iterates through all the numbers in the range, and for each number, it calls the reverse function, which itself iterates through the digits of the number. Therefore, the time complexity can be expressed as follows:

  • For each number in the range [s, e], the reverse function runs in O(d) time, where d is the number of digits in the number.
  • Let n be the difference between e and s (e - s).
  • The overall time complexity of the palindromesInRange function would be O(n * d), where d is the maximum number of digits in any number within the range.

As for the reverse function, its time complexity is O(d), where d is the number of digits in the input number.

Overall, the time complexity of the provided code is O(n * d), where n is the size of the range (e - s) and d is the maximum number of digits in any number within the range.

Last updated on by Kalkicode




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