add 2765

Author: fishercoder1534

Diff for: paginated_contents/algorithms/3rd_thousand/README.md

@@ -7,7 +7,8 @@
 | 2864 | [Maximum Odd Binary Number](https://leetcode.com/problems/maximum-odd-binary-number/)                                                                                                               | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2864.java)                                       |                                      | Easy                      |Greedy
 | 2824 | [Count Pairs Whose Sum is Less than Target](https://leetcode.com/problems/count-pairs-whose-sum-is-less-than-target/)                                                                                                               | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2824.java)                                       |                                      | Easy                      |
 | 2812 | [Find the Safest Path in a Grid](https://leetcode.com/problems/find-the-safest-path-in-a-grid/)                                                                                                               | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2812.java)                                       |                                      | Medium                    |BFS
-| 2769 | [Find the Maximum Achievable Number](https://leetcode.com/problems/find-the-maximum-achievable-number/)                                                                                                               | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2769.java)                                       |                                      | Easy                      | 
+| 2769 | [Find the Maximum Achievable Number](https://leetcode.com/problems/find-the-maximum-achievable-number/)                                                                                                               | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2769.java)                                       |                                      | Easy                      |
+| 2765 | [Longest Alternating Subarray](https://leetcode.com/problems/longest-alternating-subarray/)                                                                                                               | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2765.java)                                       |                                      | Easy                      | 
 | 2751 | [Robot Collisions](https://leetcode.com/problems/robot-collisions/)                                                                                                               | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2751.java)                                       |                                      | Hard                      | Stack, Simulation
 | 2716 | [Minimize String Length](https://leetcode.com/problems/minimize-string-length/)                                                                                                               | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2716.java)                                       | [:tv:](https://youtu.be/aMJ3T0K8LjI) | Easy                      |
 | 2710 | [Remove Trailing Zeros From a String](https://leetcode.com/problems/remove-trailing-zeros-from-a-string/)                                                                                     | [Java](https://github.com/fishercoder1534/Leetcode/blob/master/src/main/java/com/fishercoder/solutions/thirdthousand/_2710.java)                                       |                                      | Easy                      |

Diff for: src/main/java/com/fishercoder/solutions/thirdthousand/_2765.java

@@ -0,0 +1,30 @@
+package com.fishercoder.solutions.thirdthousand;
+
+public class _2765 {
+    public static class Solution1 {
+        public int alternatingSubarray(int[] nums) {
+            int len = nums.length;
+            int maxLen = -1;
+            for (int i = 0; i < len; i++) {
+                for (int j = i + 1; j < len; j++) {
+                    if (j - i + 1 > maxLen && alternating(nums, i, j)) {
+                        maxLen = j - i + 1;
+                    }
+                }
+            }
+            return maxLen;
+        }
+
+        private boolean alternating(int[] nums, int start, int finish) {
+            int expected = 1;
+            for (int i = start, j = start + 1; i < finish && j <= finish; i++, j++) {
+                if (nums[j] - nums[i] == expected) {
+                    expected = -expected;
+                } else {
+                    return false;
+                }
+            }
+            return true;
+        }
+    }
+}

Diff for: src/test/java/com/fishercoder/thirdthousand/_2765Test.java

@@ -0,0 +1,36 @@
+package com.fishercoder.thirdthousand;
+
+import com.fishercoder.solutions.thirdthousand._2765;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class _2765Test {
+    private static _2765.Solution1 solution1;
+
+    @BeforeEach
+    public void setup() {
+        solution1 = new _2765.Solution1();
+    }
+
+    @Test
+    public void test1() {
+        assertEquals(4, solution1.alternatingSubarray(new int[]{2, 3, 4, 3, 4}));
+    }
+
+    @Test
+    public void test2() {
+        assertEquals(2, solution1.alternatingSubarray(new int[]{4, 5, 6}));
+    }
+
+    @Test
+    public void test3() {
+        assertEquals(4, solution1.alternatingSubarray(new int[]{31, 32, 31, 32, 33}));
+    }
+
+    @Test
+    public void test4() {
+        assertEquals(3, solution1.alternatingSubarray(new int[]{13, 14, 15, 14}));
+    }
+}