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/**
 * // This is the interface that allows for creating nested lists.
 * // You should not implement it, or speculate about its implementation
 * class NestedInteger {
 *   public:
 *     // Return true if this NestedInteger holds a single integer, rather than a nested list.
 *     bool isInteger() const;
 *
 *     // Return the single integer that this NestedInteger holds, if it holds a single integer
 *     // The result is undefined if this NestedInteger holds a nested list
 *     int getInteger() const;
 *
 *     // Return the nested list that this NestedInteger holds, if it holds a nested list
 *     // The result is undefined if this NestedInteger holds a single integer
 *     const vector<NestedInteger> &getList() const;
 * };
 */

class NestedIterator {
    stack<NestedInteger> s;
public:
    NestedIterator(vector<NestedInteger> &nestedList) {
        for(int i=nestedList.size()-1; i>=0; i--){
            s.push(nestedList[i]);
        }
    }

    int next() {
        int tmp = s.top().getInteger();
        s.pop();
        return tmp;
    }

    bool hasNext() {
        while(!s.empty()){
            if(s.top().isInteger()) return true;
            vector<NestedInteger> tmp = s.top().getList();
            s.pop();
            for(int i=tmp.size()-1; i>=0; i--)
                s.push(tmp[i]);
        }
        return false;
    }
};

/**
 * Your NestedIterator object will be instantiated and called as such:
 * NestedIterator i(nestedList);
 * while (i.hasNext()) cout << i.next();
 */