feat: add typescript solution to lc problem: No.2309

No.2309.Greatest English Letter in Upper and Lower Case

Author: zhaocchen

solution/2300-2399/2309.Greatest English Letter in Upper and Lower Case/README.md

@@ -150,7 +150,16 @@ func greatestLetter(s string) string {
 ### **TypeScript**
 
 ```ts
-
+function greatestLetter(s: string): string {
+    let couter = new Array(128).fill(false);
+    for (let char of s) {
+        couter[char.charCodeAt(0)] = true;
+    }
+    for (let i = 90; i >= 65; i--) {
+        if (couter[i] && couter[i + 32]) return String.fromCharCode(i);
+    }
+    return '';
+};
 ```
 
 ### **...**

solution/2300-2399/2309.Greatest English Letter in Upper and Lower Case/README_EN.md

@@ -137,7 +137,16 @@ func greatestLetter(s string) string {
 ### **TypeScript**
 
 ```ts
-
+function greatestLetter(s: string): string {
+    let couter = new Array(128).fill(false);
+    for (let char of s) {
+        couter[char.charCodeAt(0)] = true;
+    }
+    for (let i = 90; i >= 65; i--) {
+        if (couter[i] && couter[i + 32]) return String.fromCharCode(i);
+    }
+    return '';
+};
 ```
 
 ### **...**

solution/2300-2399/2309.Greatest English Letter in Upper and Lower Case/Solution.ts

@@ -0,0 +1,10 @@
+function greatestLetter(s: string): string {
+    let couter = new Array(128).fill(false);
+    for (let char of s) {
+        couter[char.charCodeAt(0)] = true;
+    }
+    for (let i = 90; i >= 65; i--) {
+        if (couter[i] && couter[i + 32]) return String.fromCharCode(i);
+    }
+    return '';
+};