feat: add typescript solution to lc problem: No.1876.Substrings of Size Three with Distinct Characters (doocs#430)

Author: zhaocchen

solution/1800-1899/1876.Substrings of Size Three with Distinct Characters/README.md

@@ -81,6 +81,23 @@ class Solution {
 }
 ```
 
+### **TypeScript**
+
+```ts
+function countGoodSubstrings(s: string): number {
+    const n: number = s.length;
+    let count: number = 0;
+    for (let i: number = 0; i < n - 2; ++i) {
+        let a: string = s.charAt(i), b: string = s.charAt(i + 1), c: string = s.charAt(i + 2);
+        if (a != b && a != c && b != c) {
+            ++count;
+        }
+    }
+    return count;
+};
+
+```
+
 ### **...**
 
 ```

solution/1800-1899/1876.Substrings of Size Three with Distinct Characters/README_EN.md

@@ -71,6 +71,22 @@ class Solution {
 }
 ```
 
+### **TypeScript**
+
+```ts
+function countGoodSubstrings(s: string): number {
+    const n: number = s.length;
+    let count: number = 0;
+    for (let i: number = 0; i < n - 2; ++i) {
+        let a: string = s.charAt(i), b: string = s.charAt(i + 1), c: string = s.charAt(i + 2);
+        if (a != b && a != c && b != c) {
+            ++count;
+        }
+    }
+    return count;
+};
+```
+
 ### **...**
 
 ```

solution/1800-1899/1876.Substrings of Size Three with Distinct Characters/Solution.ts

@@ -0,0 +1,11 @@
+function countGoodSubstrings(s: string): number {
+    const n: number = s.length;
+    let count: number = 0;
+    for (let i: number = 0; i < n - 2; ++i) {
+        let a: string = s.charAt(i), b: string = s.charAt(i + 1), c: string = s.charAt(i + 2);
+        if (a != b && a != c && b != c) {
+            ++count;
+        }
+    }
+    return count;
+};