HackerRank-Solutions/Java/Advanced/Java Lambda Expressions/Solution.java

//     Author: Rodney Shaghoulian
//     Github: github.com/RodneyShag
// HackerRank: hackerrank.com/RodneyShag

import java.io.*;
import java.util.*;
interface PerformOperation {
    boolean check(int a);
}
class MyMath {
    public static boolean checker(PerformOperation p, int num) {
        return p.check(num);
    }

    public static PerformOperation is_odd() {
        return n -> (n & 1) == 1;
    }

    public static PerformOperation is_prime() {
        // O(n^(1/2)) runtime
        return n -> {
            if (n < 2) {
                return false;
            }
            int sqrt = (int) Math.sqrt(n);
            for (int i = 2; i <= sqrt; i++) {
                if (n % i == 0) {
                    return false;
                }
            }
            return true;
        };
    }

    public static PerformOperation is_palindrome() {
        return n -> {
            String original = Integer.toString(n);
            String reversed = new StringBuilder(Integer.toString(n)).reverse().toString();
            return original.equals(reversed);
        };
    }
}

public class Solution {
    public static void main(String[] args) throws IOException {
        MyMath ob = new MyMath();
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int T = Integer.parseInt(br.readLine());
        PerformOperation op;
        boolean ret = false;
        String ans = null;
        while (T--> 0) {
            String s = br.readLine().trim();
            StringTokenizer st = new StringTokenizer(s);
            int ch = Integer.parseInt(st.nextToken());
            int num = Integer.parseInt(st.nextToken());
            if (ch == 1) {
                op = ob.is_odd();
                ret = ob.checker(op, num);
                ans = (ret) ? "ODD" : "EVEN";
            } else if (ch == 2) {
                op = ob.is_prime();
                ret = ob.checker(op, num);
                ans = (ret) ? "PRIME" : "COMPOSITE";
            } else if (ch == 3) {
                op = ob.is_palindrome();
                ret = ob.checker(op, num);
                ans = (ret) ? "PALINDROME" : "NOT PALINDROME";
            }
            System.out.println(ans);
        }
    }
}