Class NestedIterator
java.lang.Object
g0301_0400.s0341_flatten_nested_list_iterator.NestedIterator
341 - Flatten Nested List Iterator.<p>Medium</p>
<p>You are given a nested list of integers <code>nestedList</code>. Each element is either an integer or a list whose elements may also be integers or other lists. Implement an iterator to flatten it.</p>
<p>Implement the <code>NestedIterator</code> class:</p>
<ul>
<li><code>NestedIterator(List<NestedInteger> nestedList)</code> Initializes the iterator with the nested list <code>nestedList</code>.</li>
<li><code>int next()</code> Returns the next integer in the nested list.</li>
<li><code>boolean hasNext()</code> Returns <code>true</code> if there are still some integers in the nested list and <code>false</code> otherwise.</li>
</ul>
<p>Your code will be tested with the following pseudocode:</p>
<pre><code> initialize iterator with nestedList
res = []
while iterator.hasNext()
append iterator.next() to the end of res
return res
</code></pre>
<p>If <code>res</code> matches the expected flattened list, then your code will be judged as correct.</p>
<p><strong>Example 1:</strong></p>
<p><strong>Input:</strong> nestedList = [[1,1],2,[1,1]]</p>
<p><strong>Output:</strong> [1,1,2,1,1]</p>
<p><strong>Explanation:</strong> By calling next repeatedly until hasNext returns false, the order of elements returned by next should be: [1,1,2,1,1].</p>
<p><strong>Example 2:</strong></p>
<p><strong>Input:</strong> nestedList = [1,[4,[6]]]</p>
<p><strong>Output:</strong> [1,4,6]</p>
<p><strong>Explanation:</strong> By calling next repeatedly until hasNext returns false, the order of elements returned by next should be: [1,4,6].</p>
<p><strong>Constraints:</strong></p>
<ul>
<li><code>1 <= nestedList.length <= 500</code></li>
<li>The values of the integers in the nested list is in the range <code>[-10<sup>6</sup>, 10<sup>6</sup>]</code>.</li>
</ul>