# GeetCode Hub

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(List<NestedInteger> nestedList)` Initializes the iterator with the nested list `nestedList`.
• `int next()` Returns the next integer in the nested list.
• `boolean hasNext()` Returns `true` if there are still some integers in the nested list and `false` otherwise.

Your code will be tested with the following pseudocode:

```initialize iterator with nestedList
res = []
while iterator.hasNext()
append iterator.next() to the end of res
return res
```

If `res` matches the expected flattened list, then your code will be judged as correct.

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 `[-106, 106]`.

/** * // This is the interface that allows for creating nested lists. * // You should not implement it, or speculate about its implementation * public interface NestedInteger { * * // @return true if this NestedInteger holds a single integer, rather than a nested list. * public boolean isInteger(); * * // @return the single integer that this NestedInteger holds, if it holds a single integer * // Return null if this NestedInteger holds a nested list * public Integer getInteger(); * * // @return the nested list that this NestedInteger holds, if it holds a nested list * // Return empty list if this NestedInteger holds a single integer * public List<NestedInteger> getList(); * } */ public class NestedIterator implements Iterator<Integer> { public NestedIterator(List<NestedInteger> nestedList) { } @Override public Integer next() { } @Override public boolean hasNext() { } } /** * Your NestedIterator object will be instantiated and called as such: * NestedIterator i = new NestedIterator(nestedList); * while (i.hasNext()) v[f()] = i.next(); */
Medium
Medium
Medium
Medium