Java - Java Lambda Expressions

Author: L9Lenny

Java/Hackerrank/Java Lambda Expressions/Solution.java

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+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);
+    }
+
+    /**
+     * Returns a lambda expression that checks if a number is odd.
+     *
+     * @return A PerformOperation that checks if a number is odd.
+     */
+
+    public static PerformOperation isOdd() {
+        return n -> (n & 1) == 1;       // Use bitwise AND to check if the number is odd
+    }
+
+    /**
+     * Returns a lambda expression that checks if a number is prime.
+     *
+     * @return A PerformOperation that checks if a number is prime.
+     */
+
+    public static PerformOperation isPrime() {
+        return n -> {
+            if (n < 2) {
+                return false;       // Numbers less than 2 are not prime
+            } else if (n == 2) {
+                return true;        // 2 is the smallest prime number
+            } else if (n % 2 == 0) {
+                return false;       // Even numbers greater than 2 are not prime
+            }
+            int sqrt = (int) Math.sqrt(n);      // Check divisibility up to the square root of the number
+            for (int i = 3; i <= sqrt; i += 2) {
+                if (n % i == 0) {
+                    return false;               // If divisible by any number, it's not prime
+                }
+            }
+            return true;                    // If no divisors were found, it's prime
+        };
+    }
+
+    /**
+     * Returns a lambda expression that checks if a number is a palindrome.
+     *
+     * @return A PerformOperation that checks if a number is a palindrome.
+     */
+
+    public static PerformOperation isPalindrome() {
+        return n -> {
+            String original = Integer.toString(n);      // Convert the number to a string
+            String reversed = new StringBuilder(Integer.toString(n)).reverse().toString();      // Reverse the string
+            return original.equals(reversed);           // Check if the original and reversed strings are equal
+        };
+    }
+}
+
+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.isOdd();
+                ret = ob.checker(op, num);
+                ans = (ret) ? "ODD" : "EVEN";
+            } else if (ch == 2) {
+                op = ob.isPrime();
+                ret = ob.checker(op, num);
+                ans = (ret) ? "PRIME" : "COMPOSITE";
+            } else if (ch == 3) {
+                op = ob.isPalindrome();
+                ret = ob.checker(op, num);
+                ans = (ret) ? "PALINDROME" : "NOT PALINDROME";
+
+            }
+            System.out.println(ans);
+        }
+    }
+}