1.反转链表LeetCode206Easy

分析：从前往后扫，一个一个扫即可。

/** * 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

class Solution {public:    vector
      
       
        > subsets(vector
        
         & nums) {        vector
         
          
           >result;        int number=1<
           

temp; for(int j=0;j