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feat: add solutions to lc problem: No.0978
No.0978.Longest Turbulent Subarray
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‎solution/0900-0999/0978.Longest Turbulent Subarray/README.md

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<!-- 这里可写通用的实现逻辑 -->
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**方法一：动态规划**
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我们定义 $f[i]$ 表示以 $nums[i]$ 结尾且结尾处于上升状态的最长湍流子数组的长度，定义 $g[i]$ 表示以 $nums[i]$ 结尾且结尾处于下降状态的最长湍流子数组的长度。初始时 $f[0] = 1$, $g[0] = 1$。答案为 $max(f[i], g[i])$。
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对于 $i \gt 0$，若 $nums[i] \gt nums[i - 1]$，则 $f[i] = g[i - 1] + 1$，否则 $f[i] = 1$；若 $nums[i] \lt nums[i - 1]$，则 $g[i] = f[i - 1] + 1$，否则 $g[i] = 1$。
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由于 $f[i]$ 和 $g[i]$ 只与 $f[i - 1]$ 和 $g[i - 1]$ 有关，因此可以使用两个变量代替数组。
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时间复杂度 $O(n)$，空间复杂度 $O(1)$。其中 $n$ 为数组长度。
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<!-- tabs:start -->
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### **Python3**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```python
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class Solution:
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def maxTurbulenceSize(self, arr: List[int]) -> int:
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ans = f = g = 1
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for a, b in pairwise(arr):
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ff = g + 1 if a < b else 1
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gg = f + 1 if a > b else 1
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f, g = ff, gg
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ans = max(ans, f, g)
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return ans
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```
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### **Java**
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<!-- 这里可写当前语言的特殊实现逻辑 -->
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```java
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class Solution {
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public int maxTurbulenceSize(int[] arr) {
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int ans = 1, f = 1, g = 1;
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for (int i = 1; i < arr.length; ++i) {
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int ff = arr[i - 1] < arr[i] ? g + 1 : 1;
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int gg = arr[i - 1] > arr[i] ? f + 1 : 1;
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f = ff;
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g = gg;
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ans = Math.max(ans, Math.max(f, g));
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}
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return ans;
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}
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}
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```
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### **C++**
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```cpp
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class Solution {
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public:
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int maxTurbulenceSize(vector<int>& arr) {
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int ans = 1, f = 1, g = 1;
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for (int i = 1; i < arr.size(); ++i) {
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int ff = arr[i - 1] < arr[i] ? g + 1 : 1;
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int gg = arr[i - 1] > arr[i] ? f + 1 : 1;
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f = ff;
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g = gg;
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ans = max({ans, f, g});
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}
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return ans;
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}
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};
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```
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### **Go**
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```go
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func maxTurbulenceSize(arr []int) int {
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ans, f, g := 1, 1, 1
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for i, x := range arr[1:] {
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ff, gg := 1, 1
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if arr[i] < x {
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ff = g + 1
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}
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if arr[i] > x {
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gg = f + 1
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}
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f, g = ff, gg
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ans = max(ans, max(f, g))
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}
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return ans
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}
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func max(a, b int) int {
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if a > b {
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return a
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}
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return b
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}
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```
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### **TypeScript**
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```ts
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function maxTurbulenceSize(arr: number[]): number {
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let f = 1;
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let g = 1;
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let ans = 1;
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for (let i = 1; i < arr.length; ++i) {
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const ff = arr[i - 1] < arr[i] ? g + 1 : 1;
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const gg = arr[i - 1] > arr[i] ? f + 1 : 1;
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f = ff;
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g = gg;
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ans = Math.max(ans, f, g);
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}
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return ans;
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}
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```
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### **...**

‎solution/0900-0999/0978.Longest Turbulent Subarray/README_EN.md

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### **Python3**
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```python
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class Solution:
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def maxTurbulenceSize(self, arr: List[int]) -> int:
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ans = f = g = 1
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for a, b in pairwise(arr):
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ff = g + 1 if a < b else 1
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gg = f + 1 if a > b else 1
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f, g = ff, gg
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ans = max(ans, f, g)
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return ans
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```
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### **Java**
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```java
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class Solution {
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public int maxTurbulenceSize(int[] arr) {
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int ans = 1, f = 1, g = 1;
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for (int i = 1; i < arr.length; ++i) {
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int ff = arr[i - 1] < arr[i] ? g + 1 : 1;
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int gg = arr[i - 1] > arr[i] ? f + 1 : 1;
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f = ff;
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g = gg;
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ans = Math.max(ans, Math.max(f, g));
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}
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return ans;
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}
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}
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```
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### **C++**
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```cpp
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class Solution {
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public:
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int maxTurbulenceSize(vector<int>& arr) {
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int ans = 1, f = 1, g = 1;
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for (int i = 1; i < arr.size(); ++i) {
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int ff = arr[i - 1] < arr[i] ? g + 1 : 1;
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int gg = arr[i - 1] > arr[i] ? f + 1 : 1;
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f = ff;
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g = gg;
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ans = max({ans, f, g});
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}
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return ans;
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}
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};
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```
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### **Go**
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```go
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func maxTurbulenceSize(arr []int) int {
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ans, f, g := 1, 1, 1
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for i, x := range arr[1:] {
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ff, gg := 1, 1
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if arr[i] < x {
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ff = g + 1
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}
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if arr[i] > x {
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gg = f + 1
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}
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f, g = ff, gg
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ans = max(ans, max(f, g))
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}
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return ans
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}
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func max(a, b int) int {
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if a > b {
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return a
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}
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return b
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}
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```
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### **TypeScript**
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```ts
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function maxTurbulenceSize(arr: number[]): number {
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let f = 1;
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let g = 1;
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let ans = 1;
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for (let i = 1; i < arr.length; ++i) {
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const ff = arr[i - 1] < arr[i] ? g + 1 : 1;
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const gg = arr[i - 1] > arr[i] ? f + 1 : 1;
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f = ff;
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g = gg;
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ans = Math.max(ans, f, g);
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}
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return ans;
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}
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```
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### **...**

‎solution/0900-0999/0978.Longest Turbulent Subarray/Solution.cpp

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class Solution {
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public:
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int maxTurbulenceSize(vector<int>& arr) {
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int ans = 1, f = 1, g = 1;
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for (int i = 1; i < arr.size(); ++i) {
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int ff = arr[i - 1] < arr[i] ? g + 1 : 1;
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int gg = arr[i - 1] > arr[i] ? f + 1 : 1;
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f = ff;
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g = gg;
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ans = max({ans, f, g});
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}
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return ans;
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}
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};

‎solution/0900-0999/0978.Longest Turbulent Subarray/Solution.go

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func maxTurbulenceSize(arr []int) int {
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ans, f, g := 1, 1, 1
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for i, x := range arr[1:] {
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ff, gg := 1, 1
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if arr[i] < x {
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ff = g + 1
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}
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if arr[i] > x {
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gg = f + 1
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}
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f, g = ff, gg
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ans = max(ans, max(f, g))
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}
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return ans
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}
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func max(a, b int) int {
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if a > b {
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return a
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}
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return b
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}

‎solution/0900-0999/0978.Longest Turbulent Subarray/Solution.java

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class Solution {
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public int maxTurbulenceSize(int[] A) {
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int res = 1;
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int up = 1, down = 1;
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for (int i = 1; i < A.length; ++i) {
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if (A[i] > A[i - 1]) {
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up = down + 1;
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down = 1;
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res = Math.max(res, up);
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} else if (A[i] < A[i - 1]) {
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down = up + 1;
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up = 1;
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res = Math.max(res, down);
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} else {
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up = 1;
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down = 1;
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}
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public int maxTurbulenceSize(int[] arr) {
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int ans = 1, f = 1, g = 1;
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for (int i = 1; i < arr.length; ++i) {
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int ff = arr[i - 1] < arr[i] ? g + 1 : 1;
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int gg = arr[i - 1] > arr[i] ? f + 1 : 1;
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f = ff;
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g = gg;
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ans = Math.max(ans, Math.max(f, g));
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}
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return res;
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return ans;
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}
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}
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}

‎solution/0900-0999/0978.Longest Turbulent Subarray/Solution.py

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class Solution:
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def maxTurbulenceSize(self, arr: List[int]) -> int:
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ans = f = g = 1
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for a, b in pairwise(arr):
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ff = g + 1 if a < b else 1
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gg = f + 1 if a > b else 1
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f, g = ff, gg
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ans = max(ans, f, g)
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return ans

‎solution/0900-0999/0978.Longest Turbulent Subarray/Solution.ts

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function maxTurbulenceSize(arr: number[]): number {
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let f = 1;
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let g = 1;
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let ans = 1;
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for (let i = 1; i < arr.length; ++i) {
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const ff = arr[i - 1] < arr[i] ? g + 1 : 1;
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const gg = arr[i - 1] > arr[i] ? f + 1 : 1;
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f = ff;
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g = gg;
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ans = Math.max(ans, f, g);
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}
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return ans;
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}

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