feat: add ts solution to lc problem: No.1911 (doocs#1192)

No.1911.Maximum Alternating Subsequence Sum

Author: yanglbme

solution/1900-1999/1911.Maximum Alternating Subsequence Sum/README.md

@@ -212,6 +212,31 @@ func max(a, b int) int {
 }
 ```
 
+### **TypeScript**
+
+```ts
+function maxAlternatingSum(nums: number[]): number {
+    const n = nums.length;
+    const f: number[] = new Array(n + 1).fill(0);
+    const g = f.slice();
+    for (let i = 1; i <= n; ++i) {
+        f[i] = Math.max(g[i - 1] + nums[i - 1], f[i - 1]);
+        g[i] = Math.max(f[i - 1] - nums[i - 1], g[i - 1]);
+    }
+    return Math.max(f[n], g[n]);
+}
+```
+
+```ts
+function maxAlternatingSum(nums: number[]): number {
+    let [f, g] = [0, 0];
+    for (const x of nums) {
+        [f, g] = [Math.max(g - x, f), Math.max(f + x, g)];
+    }
+    return g;
+}
+```
+
 ### **...**
 
 ```

solution/1900-1999/1911.Maximum Alternating Subsequence Sum/README_EN.md

@@ -180,6 +180,31 @@ func max(a, b int) int {
 }
 ```
 
+### **TypeScript**
+
+```ts
+function maxAlternatingSum(nums: number[]): number {
+    const n = nums.length;
+    const f: number[] = new Array(n + 1).fill(0);
+    const g = f.slice();
+    for (let i = 1; i <= n; ++i) {
+        f[i] = Math.max(g[i - 1] + nums[i - 1], f[i - 1]);
+        g[i] = Math.max(f[i - 1] - nums[i - 1], g[i - 1]);
+    }
+    return Math.max(f[n], g[n]);
+}
+```
+
+```ts
+function maxAlternatingSum(nums: number[]): number {
+    let [f, g] = [0, 0];
+    for (const x of nums) {
+        [f, g] = [Math.max(g - x, f), Math.max(f + x, g)];
+    }
+    return g;
+}
+```
+
 ### **...**
 
 ```

solution/1900-1999/1911.Maximum Alternating Subsequence Sum/Solution.ts

@@ -0,0 +1,7 @@
+function maxAlternatingSum(nums: number[]): number {
+    let [f, g] = [0, 0];
+    for (const x of nums) {
+        [f, g] = [Math.max(g - x, f), Math.max(f + x, g)];
+    }
+    return g;
+}