add: 最长交替子数组

README.md

@@ -165,6 +165,10 @@ Rust标准库`std::collections`提供了4种通用容器类型，包含一下8
 
 ### 数组/队列/集合/映射
 
+- [最长交替子数组](src/array/longest_alternating_subarray.rs)  [数组, 枚举]
+
+  - LeetCode 2765. 最长交替子数组 <https://leetcode.cn/problems/longest-alternating-subarray>
+
 - [分割数组的最大值](src/array/split_array_largest_sum.rs)  [贪心, 数组, 二分查找, 动态规划, 前缀和]
 
   - LeetCode 410. 分割数组的最大值 <https://leetcode.cn/problems/split-array-largest-sum>

src/array/longest_alternating_subarray.rs

@@ -0,0 +1,25 @@
+// 最长交替子数组
+// https://leetcode.cn/problems/longest-alternating-subarray
+// INLINE  ../../images/array/longest_alternating_subarray.jpeg
+
+pub struct Solution;
+
+impl Solution {
+    pub fn alternating_subarray(nums: Vec<i32>) -> i32 {
+        let mut res = -1;
+        let n = nums.len();
+        for first_index in 0..n {
+            for i in (first_index + 1)..n {
+                let length = i - first_index + 1;
+                if nums[i] - nums[first_index]
+                    == TryInto::<i32>::try_into((length - 1) % 2).unwrap()
+                {
+                    res = res.max(length as i32);
+                } else {
+                    break;
+                }
+            }
+        }
+        res
+    }
+}

src/array/mod.rs

@@ -58,3 +58,4 @@ pub mod count_common_words_with_one_occurrence;
 pub mod find_maximum_number_of_string_pairs;
 pub mod split_strings_by_separator;
 pub mod split_array_largest_sum;
+pub mod longest_alternating_subarray;

tests/array/longest_alternating_subarray_test.rs

@@ -0,0 +1,18 @@
+use rust_practice::array::longest_alternating_subarray::Solution;
+
+#[test]
+fn alternating_subarray_test() {
+    // 示例 1：
+    // 输入：nums = [2,3,4,3,4]
+    // 输出：4
+    // 解释：交替子数组有 [3,4] ，[3,4,3] 和 [3,4,3,4] 。最长的子数组为 [3,4,3,4] ，长度为4 。
+    let nums = vec![2, 3, 4, 3, 4];
+    assert_eq!(Solution::alternating_subarray(nums), 4);
+
+    // 示例 2：
+    // 输入：nums = [4,5,6]
+    // 输出：2
+    // 解释：[4,5] 和 [5,6] 是仅有的两个交替子数组。它们长度都为 2 。
+    let nums = vec![4, 5, 6];
+    assert_eq!(Solution::alternating_subarray(nums), 2);
+}

tests/array/mod.rs

@@ -58,3 +58,4 @@ pub mod zero_matrix_lcci_test;
 pub mod find_maximum_number_of_string_pairs_test;
 pub mod split_strings_by_separator_test;
 pub mod split_array_largest_sum_test;
+pub mod longest_alternating_subarray_test;