Added code of Twos Complement

Author: Monk-AbhinayVerma

src/main/java/com/thealgorithms/bitmanipulation/TwosComplement.java

@@ -0,0 +1,55 @@
+package com.thealgorithms.bitmanipulation;
+
+import java.util.Scanner;
+
+public class TwosComplement {
+
+    // Function to get the 2's complement of a binary number
+    public static String twosComplement(String binary) {
+        StringBuilder onesComplement = new StringBuilder();
+        
+        // Step 1: Find the 1's complement (invert the bits)
+        for (int i = 0; i < binary.length(); i++) {
+            if (binary.charAt(i) == '0') {
+                onesComplement.append('1');
+            } else {
+                onesComplement.append('0');
+            }
+        }
+
+        // Step 2: Add 1 to the 1's complement
+        StringBuilder twosComplement = new StringBuilder(onesComplement);
+        boolean carry = true;
+        for (int i = onesComplement.length() - 1; i >= 0; i--) {
+            if (onesComplement.charAt(i) == '1' && carry) {
+                twosComplement.setCharAt(i, '0');
+            } else if (onesComplement.charAt(i) == '0' && carry) {
+                twosComplement.setCharAt(i, '1');
+                carry = false;
+            }
+        }
+
+        // If there is still a carry, append '1' at the beginning
+        if (carry) {
+            twosComplement.insert(0, '1');
+        }
+
+        return twosComplement.toString();
+    }
+
+    public static void main(String[] args) {
+        Scanner scanner = new Scanner(System.in);
+
+        // Input a binary number
+        System.out.print("Enter a number: ");
+        int n = scanner.nextInt();
+        String binary = Integer.toBinaryString(n);
+
+        // Compute and print the 2's complement
+        String result = twosComplement(binary);
+        int num = Integer.parseInt(result, 2);
+        System.out.println("2's complement of " + n +"("+binary+")" +" is: " + num + "("+ result+")");
+
+        scanner.close();
+    }
+}