Flatten Nested List Iterator

You are given a nested list of integers nestedList. Each element is either an integer or a list whose elements may also be integers or other lists. Implement an iterator to flatten it.

Implement the NestedIterator class:

• NestedIterator(nestedList) Initializes the iterator with the nested list nestedList.
• next() Returns the next integer in the nested list.
• hasNext() Returns true if there are still some integers in the nested list and false otherwise.

Each NestedInteger has the following interface:

• isInteger() returns true if this NestedInteger holds a single integer.
• getInteger() returns the single integer this NestedInteger holds (if it holds a single integer).
• getList() returns the nested list this NestedInteger holds (if it holds a nested list).

Examples

Example 1:

Input: nestedList = [[1,1],2,[1,1]]

Output: [1,1,2,1,1]

Explanation: By calling next repeatedly until hasNext returns false, the order of elements returned by next should be: [1,1,2,1,1].

Example 2:

Input: nestedList = [1,[4,[6]]]

Output: [1,4,6]

Explanation: By calling next repeatedly until hasNext returns false, the order of elements returned by next should be: [1,4,6].

Constraints

• 1 <= nestedList.length <= 500
• The values of the integers in the nested list is in the range [-10^6, 10^6]