recursion moving char to the end of the string

Question

i need to get a string and rearrange it with recursion by getting char and by that char i have to move that char everywhere on the string to the end like \"Hello world!\" ,\'l\

Answer 1

If you use recursion, it will be pretty expensive call for the result you are expecting. Lot of movement of String or charArray elements, eitherway you do. I don't see its a wiser choice. I would do it this way, it will be of space complexity O(2n) & performance complexity O(n).

public class Solve {
public static void main(String[] args) {
    System.out.println(ChToLast("Hello world!", 'l'));
}

public static String ChToLast(String str, char ch) {
    char[] chars = str.toCharArray();
    char[] modChars = new char[chars.length];
    int i = 0;      
    for(char element : chars){
        if(ch != element){
            modChars[i++] = element;
        }
    }
    Arrays.fill(modChars, i, chars.length , ch);
    return new String(modChars);
}   
}