题目：

题解：

class NestedIterator {
private:
    vector<int> vals;
    vector<int>::iterator cur;

    void dfs(const vector<NestedInteger> &nestedList) {
        for (auto &nest : nestedList) {
            if (nest.isInteger()) {
                vals.push_back(nest.getInteger());
            } else {
                dfs(nest.getList());
            }
        }
    }

public:
    NestedIterator(vector<NestedInteger> &nestedList) {
        dfs(nestedList);
        cur = vals.begin();
    }

    int next() {
        return *cur++;
    }

    bool hasNext() {
        return cur != vals.end();
    }
};