剑指offer c++

3.从你头到尾打印链表

/**
*  struct ListNode {
*        int val;
*        struct ListNode *next;
*        ListNode(int x) :
*              val(x), next(NULL) {
*        }
*  };
*/
class Solution {
public:
    vector<int> printListFromTailToHead(ListNode* head) {
        vector<int> v1;
        vector<int> v2;
        if(!head) return v2;
        while(head){
            v1.push_back(head->val);
            head = head->next;
        }
        for(vector<int>::iterator iter=v1.end()-1;iter!=v1.begin()-1;iter--){
            v2.push_back(*iter);
        }
        return v2;
    }
};

重建二叉树：
 

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    TreeNode* reConstructBinaryTree(vector<int> pre,vector<int> vin) {
        if(pre.size()==0) return NULL;
        TreeNode* t=new TreeNode(pre[0]);
        int index = -1;
        for(int i=0;i<vin.size();i++){
            if(vin[i]==pre[0])
                index = i;
        }
        vector<int> v1(pre.begin()+(index?1:0),pre.begin()+(index?index+1:index));
        vector<int> v2(vin.begin(),vin.begin()+index);
        vector<int> v3(pre.begin()+index+1,pre.end());
        vector<int> v4(vin.begin()+index+1,vin.end());
        t->left = reConstructBinaryTree(v1,v2);
        t->right = reConstructBinaryTree(v3,v4);
        return t;
    }
};