添加（0738.单调递增的数字.md）：增加typescript版本

problems/0738.单调递增的数字.md

@@ -225,6 +225,28 @@ var monotoneIncreasingDigits = function(n) {
 };
 ```
 
+### TypeScript
+
+```typescript
+function monotoneIncreasingDigits(n: number): number {
+    let strArr: number[] = String(n).split('').map(i => parseInt(i));
+    const length = strArr.length;
+    let flag: number = length;
+    for (let i = length - 2; i >= 0; i--) {
+        if (strArr[i] > strArr[i + 1]) {
+            strArr[i] -= 1;
+            flag = i + 1;
+        }
+    }
+    for (let i = flag; i < length; i++) {
+        strArr[i] = 9;
+    }
+    return parseInt(strArr.join(''));
+};
+```
+
+
+
 
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