Maximum number of characters using keystrokes A, Ctrl+A, Ctrl+C and Ctrl+V

Question

This is an interview question from google. I am not able to solve it by myself. Can somebody shed some light?

Write a program to print the sequence of keystrokes suc

Answer 1

public int dp(int n) 
{
    int arr[] = new int[n];
    for (int i = 0; i < n; i++)
        arr[i] = i + 1;
    for (int i = 2; i < n - 3; i++) 
    {
        int numchars = arr[i] * 2;
        int j = i + 3;
        arr[j] = Math.max(arr[j], numchars);
        while (j < n - 1) 
        {
            numchars = numchars + arr[i];
            arr[++j] = Math.max(arr[j], numchars);
        }
    }
    return arr[n - 1];
}