lintcode 平面列表

问题描述：

给定一个列表，该列表中的每个要素要么是个列表，要么是整数。将其变成一个只包含整数的简单列表。

样例：

给定 [1,2,[1,2]]，返回 [1,2,1,2]。

给定 [4,[3,[2,[1]]]]，返回 [4,3,2,1]。

 /**
  * // 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 Solution {
 public:
     // @param nestedList a list of NestedInteger
     // @return a list of integer
     vector<int> result;
     vector<int> flatten(const vector<NestedInteger> &nestedList) {
         int nums = nestedList.size();

         for (int i = ; i < nums; i++) {
             if (nestedList[i].isInteger()) {
                 result.push_back(nestedList[i].getInteger());
             } else {
                 flatten(nestedList[i].getList());
             }
         }
         return result;
     }
 };