Keypad_Problems.java

package Some_important_algos;

public class Keypad_Problems {
    public static String getString(int num) {
        if (num == 2) {
            return "abc";
        }
        if (num == 3) {
            return "def";
        }
        if (num == 4) {
            return "ghi";
        }
        if (num == 5) {
            return "jkl";
        }
        if (num == 6) {
            return "mno";
        }
        if (num == 7) {
            return "pqrs";
        }
        if (num == 8) {
            return "tuv";
        }
        if (num == 9) {
            return "wxyz";
        }
        return "";
    }

    public static String[] keystring(int num) {
        if (num == 0) {
            String[] arr = new String[1];
            arr[0] = "";
            return arr;
        }
        String[] smalloutput = keystring(num / 10);
        String length = getString(num % 10);
        String[] output = new String[smalloutput.length * length.length()];
        int index = 0;
        for (int i = 0; i < smalloutput.length; i++) {
            for (int j = 0; j < length.length(); j++) {
                output[index] = smalloutput[i] + length.charAt(j);
                index++;
            }
        }
        return output;
    }

    public static void printkeystring(int num, String output) {
        if (num == 0) {
            System.out.println(output);
            return;
        }
        String get = getString(num % 10);
        for (int i = 0; i < get.length(); i++) {
            printkeystring(num / 10, (get.charAt(i) + output));
        }
    }

    public static void main(String[] args) {
        printkeystring(23, "");
        // String []arr=keystring(23);
        // for(int i=0;i<arr.length;i++){
        // System.out.println(arr[i]);
        // }
    }
}