一、题目

二、示例

输入：nestedList = [[1,1],2,[1,1]]
输出：[1,1,2,1,1]
解释：通过重复调用 next 直到 hasNext 返回 false，next 返回的元素的顺序应该是: [1,1,2,1,1]。

输入：nestedList = [1,[4,[6]]]
输出：[1,4,6]
解释：通过重复调用 next 直到 hasNext 返回 false，next 返回的元素的顺序应该是: [1,4,6]。

三、思路
这里他给了一些方法，我们可以直接进行使用，比如说:isInteger(),getInteger(),getList()。然后我们在代码中就可以使用这些方法了。比较类似于数组的扁平化。
四、代码展示

/**
 * // This is the interface that allows for creating nested lists.
 * // You should not implement it, or speculate about its implementation
 * function NestedInteger() {
 *
 *     Return true if this NestedInteger holds a single integer, rather than a nested list.
 *     @return {boolean}
 *     this.isInteger = function() {
 *         ...
 *     };
 *
 *     Return the single integer that this NestedInteger holds, if it holds a single integer
 *     Return null if this NestedInteger holds a nested list
 *     @return {integer}
 *     this.getInteger = function() {
 *         ...
 *     };
 *
 *     Return the nested list that this NestedInteger holds, if it holds a nested list
 *     Return null if this NestedInteger holds a single integer
 *     @return {NestedInteger[]}
 *     this.getList = function() {
 *         ...
 *     };
 * };
 */
/**
 * @constructor
 * @param {NestedInteger[]} nestedList
 */
var NestedIterator = function (nestedList) {
    this.vals = []
    const rec = (nest) => {
        for (let item of nest) {
            if (item.isInteger()) {
                this.vals.push(item.getInteger())
            } else {
                rec(item.getList())
            }
        }
    }
    rec(nestedList)
};

/**
 * @this NestedIterator
 * @returns {boolean}
 */
NestedIterator.prototype.hasNext = function () {
    return this.vals.length > 0
};

/**
 * @this NestedIterator
 * @returns {integer}
 */
NestedIterator.prototype.next = function () {
    return this.vals.shift()
};

/**
 * Your NestedIterator will be called like this:
 * var i = new NestedIterator(nestedList), a = [];
 * while (i.hasNext()) a.push(i.next());
*/

五、总结