341. Flatten Nested List Iterator

Given a nested list of integers, implement an iterator to flatten it.

Each element is either an integer, or a list – whose elements may also be integers or other lists.

Example 1:
Given the list [[1,1],2,[1,1]],

By calling next repeatedly until hasNext returns false, the order of elements returned by next should be: [1,1,2,1,1].

Example 2:
Given the list [1,[4,[6]]],

By calling next repeatedly until hasNext returns false, the order of elements returned by next should be: [1,4,6].

思路：主要是将vector中的每个元素中的整数元素存储到数组中即可，中间用到一个递归的过程。

/** * // 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 {private:    int index;    vector<int> res;public:    void getInter(NestedInteger& temp){        if (temp.isInteger()){            res.push_back(temp.getInteger());            return;        }        const vector<NestedInteger> data = temp.getList();        for (auto x : data){            getInter(x);        }    }    NestedIterator(vector<NestedInteger> &nestedList) {        for (auto x : nestedList){            getInter(x);        }        index = 0;    }    int next() {        return res[index++];    }    bool hasNext() {        return index < res.size();    }};/** * Your NestedIterator object will be instantiated and called as such: * NestedIterator i(nestedList); * while (i.hasNext()) cout << i.next(); */