leetcode 978. Longest Turbulent Subarray | 978. 最长湍流子数组（Java）

喜欢ヅ旅行 2022-09-11 11:25 130阅读 0赞

## 题目 ##

[https://leetcode.com/problems/longest-turbulent-subarray/][https_leetcode.com_problems_longest-turbulent-subarray]  
![在这里插入图片描述][watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5a-S5rOJSHE_size_20_color_FFFFFF_t_70_g_se_x_16]

## 题解 ##

虽然 similar questions 没列出来，但能想到之前做过的（至少题目看起来）类似的题：

*  [leetcode 324. Wiggle Sort II | 324. 摆动排序 II（降序穿插）  
    ][leetcode 324. Wiggle Sort II _ 324. _ II_]
 *  [leetcode 376. Wiggle Subsequence | 376. 摆动序列（动态规划）][leetcode 376. Wiggle Subsequence _ 376.]

本题思路：

![在这里插入图片描述][watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5a-S5rOJSHE_size_20_color_FFFFFF_t_70_g_se_x_16 1]

class Solution { 
        public int maxTurbulenceSize(int[] arr) { 
            int preSign = 0; // 0:前==后 -1:前>后 1:前<后
            int cur = 1;
            int result = 1;
            for (int i = 1; i < arr.length; i++) { 
                int curSign = Integer.compare(arr[i], arr[i - 1]);
                if (curSign * preSign == -1) {  // 前后符号相反
                    cur++;
                } else { 
                    cur = curSign == 0 ? 1 : 2;
                }
                preSign = curSign;
                result = Math.max(result, cur);
            }
            return result;
        }
    }

![在这里插入图片描述][watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5a-S5rOJSHE_size_20_color_FFFFFF_t_70_g_se_x_16 2]

[https_leetcode.com_problems_longest-turbulent-subarray]: https://leetcode.com/problems/longest-turbulent-subarray/
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5a-S5rOJSHE_size_20_color_FFFFFF_t_70_g_se_x_16]: /images/20220828/8b72d6889da54baf9808e50adc74f6b4.png
[leetcode 324. Wiggle Sort II _ 324. _ II_]: https://blog.csdn.net/sinat_42483341/article/details/118672742
[leetcode 376. Wiggle Subsequence _ 376.]: https://blog.csdn.net/sinat_42483341/article/details/119000202
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5a-S5rOJSHE_size_20_color_FFFFFF_t_70_g_se_x_16 1]: /images/20220828/4a98e7b7d72e4c0892c0dc69cfdc1fd6.png
[watermark_type_ZHJvaWRzYW5zZmFsbGJhY2s_shadow_50_text_Q1NETiBA5a-S5rOJSHE_size_20_color_FFFFFF_t_70_g_se_x_16 2]: /images/20220828/b8ce294d3d7648a484052d21d2df3325.png