返回用户自定义代码部分.

返回用户代码起始行.

Parse ..

ParseFromURL param: https://leetcode-cn.com/problems/k-th-symbol-in-grammar param: https://leetcode-cn.com/problems/k-th-symbol-in-grammar/solution/ param: leetcode-cn.com/problems/k-th-symbol-in-grammar.

ProblemID2name return problem info.