Lintcode 摊平嵌套的列表

 /**
  * // 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 {
 public:
     vector<int> v;
     int cnt;
     int nested_size;
     NestedIterator(vector<NestedInteger> &nestedList) {
         // Initialize your data structure here.
         v.clear();
         cnt = ;
         dfs(nestedList);
         nested_size = v.size();
     }

     // @return {int} the next element in the iteration
     int next() {
         // Write your code here
         return v[cnt++];
     }

     // @return {boolean} true if the iteration has more element or false
     bool hasNext() {
         // Write your code here
         if(nested_size){
                 nested_size = nested_size - ;
                 return true;
         } else {
                 return false;
         }
     }

         void dfs(vector<NestedInteger> nestedList){
                 for(int i = ; i < nestedList.size(); ++i){
                         if(nestedList[i].isInteger()){
                                 v.push_back(nestedList[i].getInteger());
                         } else {
                                 dfs(nestedList[i].getList());
                         }
                 }
         }
 };
 /**
  * Your NestedIterator object will be instantiated and called as such:
  * NestedIterator i(nestedList);
  * while (i.hasNext()) v.push_back(i.next());
  */