Lexicographically largest string with sum of characters equal to N

Given a positive integer N, the task is to find the lexicographically largest string consisting of lower-case English alphabets such that the sum of the characters of the string equals N where ‘a’ = 1, ‘b’ = 2, ‘c’ = 3, ..... , and ‘z’ = 26.

Examples:

Input: N = 30
Output: zd
Explanation:
The lexicographically largest string formed is "zd" whose sum of position of characters is (26 + 4) = 30(= N).

Input: N = 14
Output: n

Approach: To make lexicographically the largest string, the idea is to print the character z, N/26 number of times and then the character at (N%26 + 1)^th position in the English alphabets. Follow the steps below to solve the problem:

• Initialize a string, say ans, that stores the required lexicographically largest string.
• Iterate until N is at least 26 and perform the following steps:
  • Add the character z to the string ans.
  • Decrement the value of N by 26.
• Add the value of char(N + 'a') to the string ans.
• After completing the above steps, print the value of ans as the resultant string.

Below is the implementation of the above approach:

// C++ program for the above approach 

#include <bits/stdc++.h> 
using namespace std; 

// Function to construct the 
// lexicographically largest string 
// having sum of characters as N 
string getString(int N) 
{ 
  
    // Stores the resulting string 
    string ans = ""; 

    // Iterate until N is at least 26 
    while (N >= 26) { 

        // Append 'z' to the string ans 
        ans += 'z'; 

        // Decrement N by 26 
        N -= 26; 
    } 

    // Append character at index (N + 'a') 
    ans += char(N + 'a' - 1); 

    // Return the resultant string 
    return ans; 
} 

// Driver Code 
int main() 
{ 
    int N = 30; 
    cout << getString(N); 

    return 0; 
} 

// java program for the above approach
import java.io.*;
import java.lang.*;
import java.util.*;

public class GFG {

    // Function to construct the
    // lexicographically largest string
    // having sum of characters as N
    static String getString(int N)
    {

        // Stores the resulting string
        String ans = "";

        // Iterate until N is at least 26
        while (N >= 26) {

            // Append 'z' to the string ans
            ans += 'z';

            // Decrement N by 26
            N -= 26;
        }

        // Append character at index (N + 'a')
        ans += (char)(N + 'a' - 1);

        // Return the resultant string
        return ans;
    }

    // Driver Code
    public static void main(String[] args)
    {

        int N = 30;
        System.out.print(getString(N));
    }
}

// This code is contributed by Kingash.

# Python3 program for the above approach

# Function to construct the
# lexicographically largest string
# having sum of characters as N
def getString(N):
  
    # Stores the resulting string
    ans = ""

    # Iterate until N is at least 26
    while (N >= 26):

        # Append 'z' to the string ans
        ans += 'z'

        # Decrement N by 26
        N -= 26

    # Append  character at index (N + 'a')
    ans += chr(N + ord('a') - 1)

    # Return the resultant string
    return ans

# Driver Code
if __name__ == '__main__':
    N = 30
    print(getString(N))

# This code is contributed by mohit kumar 29.

// C# program for the above approach
using System;

public class GFG {

    // Function to construct the
    // lexicographically largest string
    // having sum of characters as N
    static string getString(int N)
    {

        // Stores the resulting string
        string ans = "";

        // Iterate until N is at least 26
        while (N >= 26) {

            // Append 'z' to the string ans
            ans += 'z';

            // Decrement N by 26
            N -= 26;
        }

        // Append character at index (N + 'a')
        ans += (char)(N + 'a' - 1);

        // Return the resultant string
        return ans;
    }

    // Driver Code
    public static void Main(string[] args)
    {

        int N = 30;
        Console.WriteLine(getString(N));
    }
}

// This code is contributed by ukasp.

<script>
    // Javascript program for the above approach

// Function to construct the
// lexicographically largest string
// having sum of characters as N
function getString(N){

    // Stores the resulting string
    let ans = ""

    // Iterate until N is at least 26
    while (N >= 26){

        // Append 'z' to the string ans
        ans += 'z'

        // Decrement N by 26
        N -= 26
    }
    // Append character at index (N + 'a')
    ans += String.fromCharCode(N + 'a'.charCodeAt(0) - 1)

    // Return the resultant string
    return ans
}

// Driver Code
    let N = 30
    document.write(getString(N))

// This code is contributed by Saurabh Jaiswal
</script>

zd

Time Complexity: O(N)
Auxiliary Space: O(N)