Find the String having each substring with exactly K distinct characters

Given two integers N and K. The task is to find the string of length N, such that each substring of length greater than equal to K, has exactly K distinct characters. 

Examples:

Input: N=10, K=3
Output : ABCABCABCA
Explanation: The output string has 3 distinct characters.

Input : N=20, K=7
Output : ABCDEFGABCDEFGABCDEF
Explanation: The output string has 7 distinct characters.

Approach:
To solve the problem mentioned above the main idea is to print distinct elements up to length K, and then repeat the same elements up to N. 
Below is the implementation of the above approach:

C++

// C++ Program to Find the
// String having each substring
// with exactly K distinct characters
#include <bits/stdc++.h>
using namespace std;

// Function to find the
// required output string
void findString(int N, int K)
{
    // Each element at index
    // i is modulus of K
    for (int i = 0; i < N; i++) {

        cout << char('A' + i % K);
    }
}

// Driver code
int main()
{
    // initialise integers N and K
    int N = 10;
    int K = 3;

    findString(N, K);

    return 0;
}

Java

// Java program to find the
// string having each substring
// with exactly K distinct characters
import java.io.*;

class GFG {

// Function to find the
// required output string
static void findString(int N, int K)
{

    // Each element at index
    // i is modulus of K
    for (int i = 0; i < N; i++)
    {
        System.out.print((char)('A' + i % K));
    }
}

// Driver code
public static void main(String[] args)
{
    // Initialise integers N and K
    int N = 10;
    int K = 3;
    findString(N, K);
}
}

// This code is contributed by shivanisinghss2110

Python3

# Python3 Program to Find the
# String having each substring
# with exactly K distinct characters

# Function to find the
# required output string
def findString(N, K) :
    # Each element at index
    # i is modulus of K
    for i in range(N) :

        print(chr(ord('A') + i % K),end="");

# Driver code
if __name__ == "__main__" :
    # initialise integers N and K
    N = 10;
    K = 3;

    findString(N, K);

# This code is contributed by AnkitRai01

C#

// C# program to find the
// string having each substring
// with exactly K distinct characters
using System;

class GFG {

// Function to find the
// required output string
static void findString(int N, int K)
{

    // Each element at index
    // i is modulus of K
    for(int i = 0; i < N; i++)
    {
       Console.Write((char)('A' + i % K));
    }
}

// Driver code
public static void Main(String[] args)
{

    // Initialise integers N and K
    int N = 10;
    int K = 3;

    findString(N, K);
}
}

// This code is contributed by 29AjayKumar

Javascript

<script>
    // Javascript Program to Find the
    // String having each substring
    // with exactly K distinct characters

    // Function to find the
    // required output string
    function findString(N, K)
    {

        // Each element at index
        // i is modulus of K
        for (let i = 0; i < N; i++)
        {
            document.write(String.fromCharCode('A'.charCodeAt() + i % K));
        }
    }

    // initialise integers N and K
    let N = 10;
    let K = 3;

    findString(N, K);

// This code is contributed by divyesh072019.
</script>

Output:

ABCABCABCA

Time Complexity:O(N)
Auxiliary Space: O(1)