fix: 运算符优先级bug

Author: azl397985856

problems/342.power-of-four.md

@@ -72,7 +72,7 @@ return num == 1;
 代码如下：
 
 ```js
-return num > 0 && num & (num - 1 === 0) && (num - 1) % 3 === 0;
+return num > 0 && (num & (num - 1)) === 0 && (num - 1) % 3 === 0;
 ```
 
 ## 关键点