Given a string s represents the serialization of a nested list, implement a parser to deserialize it and return the deserialized NestedInteger.
Each element is either an integer or a list whose elements may also be integers or other lists.
Example 1:
Input: s = "324" Output: 324 Explanation: You should return a NestedInteger object which contains a single integer 324. Example 2:
Input: s = "[123,[456,[789]]]" Output: [123,[456,[789]]] Explanation: Return a NestedInteger object containing a nested list with 2 elements:
- An integer containing value 123.
- A nested list containing two elements: i. An integer containing value 456. ii. A nested list with one element: a. An integer containing value 789
using a stack to simulate the traversal of the syntax tree. append to current node, backtrack to upper level, or create a deeper node by next symbols.