Problem 7:
Given a list, each element in the list can be a list or integer. flatten it into a simply list with integers.
Example
Given [1,2,[1,2]]
, return [1,2,1,2]
.
Given [4,[3,[2,[1]]]]
, return [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> flatten(vector<NestedInteger> &nestedList) { // Write your code here vector<int> target; int num = nestedList.size(); for(int i = 0; i< num; i++){ if(nestedList[i].isInteger()) target.push_back(nestedList[i].getInteger()); else{ vector<NestedInteger> sub_list = nestedList[i].getList(); auto temp = flatten(sub_list); target.insert(target.end(), temp.begin(), temp.end()); } } return target; } };递归发现一篇讲的很好的文章,特此推荐: