Saturday, October 11, 2025
HomeData Modelling & AIDemlo number (Square of 11…1)

Demlo number (Square of 11…1)

Given a number of the form 11..1 such that number of digits in it is smaller than 10, find square of the number.
Examples: 
 

Input : 111111
Output : 12345654321

Input : 1111
Output : 1234321

 

Squares of 11…1 (where length is smaller than 10) are called Demlo numbers. A demlo number is number which consist of 1, 2, 3….n, n-1, n-2, …..1. 
Demlo numbers are: 
 

1 = 1
11 * 11 = 121
111 * 111 = 12321
1111 * 1111 = 1234321

To find demlo number, first we find append n numbers which are increasing and then append numbers which are decreasing.
 

C++




// CPP program to print DemloNumber
#include <bits/stdc++.h>
using namespace std;
  
// To return demlo number. This function assumes
// that the length of str is smaller than 10.
string printDemlo(string str)
{
    int len = str.length();
    string res = "";
  
    // Add numbers to res upto size
    // of str and then add number
    // reverse to it
    for (int i = 1; i <= len; i++)
        res += char(i + '0');
  
    for (int i = len - 1; i >= 1; i--)
        res += char(i + '0');
  
    return res;
}
  
// Driver program to test printDemlo()
int main()
{
    string str = "111111";
    cout << printDemlo(str);
    return 0;
}


Java




// Java program to print DemloNumber
public class Main {
  
    // To return demlo number. This function assumes
    // that the length of str is smaller than 10.
    static String printDemlo(String str)
    {
        int len = str.length();
        String res = "";
  
        // Add numbers to res upto size
        // of str and then add number
        // reverse to it
        for (int i = 1; i <= len; i++)
            res += Integer.toString(i);
  
        for (int i = len - 1; i >= 1; i--)
            res += Integer.toString(i);
  
        return res;
    }
  
    // Driver program to test printDemlo()
    public static void main(String[] args)
    {
        String str = "111111";
        System.out.println(printDemlo(str));
    }
}


Python3




# Python program to print Demlo Number
  
# To return demlo number
# Length of s is smaller than 10
def printDemlo(s):
    l = len(s)
    res = ""
      
    # Add numbers to res upto size
    # of s then add in reverse
      
    for i in range(1,l+1):
        res = res + str(i)
      
    for i in range(l-1,0,-1):
        res = res + str(i)
      
    return res
      
  
# Driver Code
s = "111111"    
print (printDemlo(s))
  
# Contributed by Harshit Agrawal


C#




// C# program to print DemloNumber
using System;
public class GFG {
  
    // To return demlo number. This function assumes
    // that the length of str is smaller than 10.
    static String printDemlo(String str)
    {
        int len = str.Length;
        String res = "";
  
        // Add numbers to res upto size
        // of str and then add number
        // reverse to it
        for (int i = 1; i <= len; i++)
            res += i.ToString();
  
        for (int i = len - 1; i >= 1; i--)
            res += i.ToString();
  
        return res;
    }
  
    // Driver program to test printDemlo()
    public static void Main()
    {
        String str = "111111";
        Console.WriteLine(printDemlo(str));
    }
}
// This code is contributed by mits


PHP




<?php
// PHP program to print DemloNumber
  
// To return demlo number. This function 
// assumes that the length of str is 
// smaller than 10.
function printDemlo($str)
{
    $len = strlen($str);
    $res = "";
  
    // Add numbers to res upto size
    // of str and then add number
    // reverse to it
    for ($i = 1; $i <= $len; $i++)
        $res .= chr($i + 48);
  
    for ($i = $len - 1; $i >= 1; $i--)
        $res .= chr($i + 48);
  
    return $res;
}
  
// Driver Code
$str = "111111";
echo printDemlo($str);
  
// This code is contributed by mits
?>


Javascript




<script>
  
// Javascript program to print DemloNumber
  
    // To return demlo number. This function assumes
    // that the length of str is smaller than 10.
    function printDemlo(str)
    {
        let len = str.length;
        let res = "";
    
        // Add numbers to res upto size
        // of str and then add number
        // reverse to it
        for (let i = 1; i <= len; i++)
            res += i.toString();
    
        for (let i = len - 1; i >= 1; i--)
            res += i.toString();
    
        return res;
    }
      
// driver program
        let str = "111111";
        document.write(printDemlo(str));
    
  // This code is contributed by susmitakundugoaldanga.
</script>


Output: 
 

12345654321

Time complexity: O(log N) where N is the length of string “str” of number n

Auxiliary space: O(1) because it is using constant space

If you like neveropen and would like to contribute, you can also write an article using write.geeksforgeeks.org or mail your article to review-team@geeksforgeeks.org. See your article appearing on the neveropen main page and help other Geeks.
Please write comments if you find anything incorrect, or you want to share more information about the topic discussed above.
 

Feeling lost in the world of random DSA topics, wasting time without progress? It’s time for a change! Join our DSA course, where we’ll guide you on an exciting journey to master DSA efficiently and on schedule.
Ready to dive in? Explore our Free Demo Content and join our DSA course, trusted by over 100,000 neveropen!

RELATED ARTICLES

Most Popular

Dominic
32350 POSTS0 COMMENTS
Milvus
87 POSTS0 COMMENTS
Nango Kala
6720 POSTS0 COMMENTS
Nicole Veronica
11882 POSTS0 COMMENTS
Nokonwaba Nkukhwana
11941 POSTS0 COMMENTS
Shaida Kate Naidoo
6839 POSTS0 COMMENTS
Ted Musemwa
7101 POSTS0 COMMENTS
Thapelo Manthata
6794 POSTS0 COMMENTS
Umr Jansen
6794 POSTS0 COMMENTS