update exercises

data/2.算法中阶/3.leetcode-字符串/4.38-外观数列/solution.md

@@ -51,14 +51,14 @@
     <pre><strong>输入：</strong>n = 4
 <strong><br />输出：</strong>"1211"
 <strong><br />解释：</strong>
-countAndSay(1) = "1"
+</pre>
 
+```
+countAndSay(1) = "1"
 countAndSay(2) = 读 "1" = 一 个 1 = "11"
-
 countAndSay(3) = 读 "11" = 二 个 1 = "21"
-
 countAndSay(4) = 读 "21" = 一 个 2 + 一 个 1 = "12" + "11" = "1211"
-</pre>
+```
 
     <p>&nbsp;</p>