leetcode

0 class NestedIterator {

1 stack<pair<vector<NestedInteger> *, int>> st;

2

3 public:

4 NestedIterator(vector<NestedInteger> &nestedList) { st.push({&nestedList, 0}); }

5 int next() {

6 if (!hasNext()) return -1;

7 auto &elem = st.top();

8 return (*elem.first)[elem.second++].getInteger();

9 }

10

11 bool hasNext() {

12 while (!st.empty()) {

13 auto &elem = st.top();

14 if (elem.second == elem.first->size()) {

15 st.pop();

16 continue;

17 }

18 if ((*elem.first)[elem.second].isInteger()) return true;

19 st.push({&(*elem.first)[elem.second++].getList(), 0});

20 }

21 return false;

22 }

23 };