第1组
1.反转链表LeetCode206Easy
分析:从前往后扫,一个一个扫即可。
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
/** * Definition for singly-linked list. * struct ListNode { * int val; * ListNode *next; * ListNode(int x) : val(x), next(NULL) {} * }; */ class Solution { public: ListNode* reverseList(ListNode* head) { ListNode *new_head=NULL; while(head){ ListNode *next=head->next; head->next=new_head; new_head=head; head=next; } return new_head; } };
2求子集LeetCode78Medium
分析:位运算回溯
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
class Solution { public: vector<vector<int>> subsets(vector<int>& nums) { vector<vector<int>>result; int number=1<<nums.size(); for(int i=0;i<number;i++){ vector<int> temp; for(int j=0;j<nums.size();j++){ if(i&1<<j){ temp.push_back(nums[j]); } } result.push_back(temp); } return result; } };