查看“︁Leetcode top75”︁的源代码

Array/String:

* 1768. Merge Strings Alternately: use StringBuilder
* 1071. Greatest Common Divisor of Strings:
if str1 and str2 can be divided, then 
<math>
str1 + str2 = str2 + str1
\gcd(a,b)=\gcd(b,a \bmod b)
</math>
just get the substring of gcd length