feat: add typescript solution to lc problem: No.0680.Valid Palindrome II (doocs#432)

Author: zhaocchen

solution/0600-0699/0680.Valid Palindrome II/README.md

@@ -86,6 +86,28 @@ class Solution {
 }
 ```
 
+### **TypeScript**
+
+```ts
+function validPalindrome(s: string): boolean {
+    for (let i: number = 0, j = s.length - 1; i < j; ++i, --j) {
+        if (s.charAt(i) != s.charAt(j)) {
+            return isPalinddrome(s.slice(i, j)) || isPalinddrome(s.slice(i + 1, j + 1));
+        }
+    }
+    return true;
+};
+
+function isPalinddrome(s: string): boolean {
+    for (let i: number = 0, j = s.length - 1; i < j; ++i, --j) {
+        if (s.charAt(i) != s.charAt(j)) {
+            return false;
+        }
+    }
+    return true;
+}
+```
+
 ### **...**
 
 ```

solution/0600-0699/0680.Valid Palindrome II/README_EN.md

@@ -99,6 +99,28 @@ class Solution {
 }
 ```
 
+### **TypeScript**
+
+```ts
+function validPalindrome(s: string): boolean {
+    for (let i: number = 0, j = s.length - 1; i < j; ++i, --j) {
+        if (s.charAt(i) != s.charAt(j)) {
+            return isPalinddrome(s.slice(i, j)) || isPalinddrome(s.slice(i + 1, j + 1));
+        }
+    }
+    return true;
+};
+
+function isPalinddrome(s: string): boolean {
+    for (let i: number = 0, j = s.length - 1; i < j; ++i, --j) {
+        if (s.charAt(i) != s.charAt(j)) {
+            return false;
+        }
+    }
+    return true;
+}
+```
+
 ### **...**
 
 ```

solution/0600-0699/0680.Valid Palindrome II/Solution.ts

@@ -0,0 +1,17 @@
+function validPalindrome(s: string): boolean {
+    for (let i: number = 0, j = s.length - 1; i < j; ++i, --j) {
+        if (s.charAt(i) != s.charAt(j)) {
+            return isPalinddrome(s.slice(i, j)) || isPalinddrome(s.slice(i + 1, j + 1));
+        }
+    }
+    return true;
+};
+
+function isPalinddrome(s: string): boolean {
+    for (let i: number = 0, j = s.length - 1; i < j; ++i, --j) {
+        if (s.charAt(i) != s.charAt(j)) {
+            return false;
+        }
+    }
+    return true;
+}