Add palindrome and two sums problems

algorithms-data-structs/src/main/java/com/xtenzq/arrays/TwoPointers.java

@@ -0,0 +1,34 @@
+package com.xtenzq.arrays;
+
+public class TwoPointers {
+
+    public static boolean isPalindrome(String input) {
+        int start = 0;
+        int end = input.length() - 1;
+        while (start < end) {
+            if (input.charAt(start) != input.charAt(end)) {
+                return false;
+            }
+            start++;
+            end--;
+        }
+        return true;
+    }
+
+    public static boolean canBeSummed(int[] sortedArray, int target) {
+        int start = 0;
+        int end = sortedArray.length - 1;
+        while (start < end) {
+            int sum = sortedArray[start] + sortedArray[end];
+            if (sum == target) {
+                return true;
+            }
+            if (sum > target) {
+                end--;
+            } else {
+                start++;
+            }
+        }
+        return false;
+    }
+}

algorithms-data-structs/src/test/java/com/xtenzq/arrays/TwoPointersTest.java

@@ -0,0 +1,28 @@
+package com.xtenzq.arrays;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class TwoPointersTest {
+
+    @Test
+    void shouldReturnTrueIfPalindrome() {
+        assertTrue(TwoPointers.isPalindrome("racecar"));
+    }
+
+    @Test
+    void shouldReturnFalseIfNotPalindrome() {
+        assertFalse(TwoPointers.isPalindrome("raceacar"));
+    }
+
+    @Test
+    void shouldReturnTrueIfCanBeSummed() {
+        assertTrue(TwoPointers.canBeSummed(new int[] { 1, 2, 4, 6, 8, 9, 14, 15 }, 13));
+    }
+
+    @Test
+    void shouldReturnFalseIfCantBeSummed() {
+        assertFalse(TwoPointers.canBeSummed(new int[] { 1, 2, 4, 6, 8, 9, 14, 15 }, 30));
+    }
+}