剑指offer-重建二叉树

 1 /**
 2  * Definition for binary tree
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     TreeNode* reConstructBinaryTree(vector<int> pre,vector<int> in) {
13         if(pre.empty()||in.empty())
14             return NULL;
15         return CBT(pre,in,0,pre.size()-1,0,in.size()-1);
16     }
17     TreeNode* CBT(vector<int> pre,vector<int> in,int f1,int l1,int f2,int l2){
18         TreeNode* node=new TreeNode(pre[f1]);
19         int m=f2-1;
20         while(in[++m]!=pre[f1]);
21         if(m>f2)
22             node->left=CBT(pre,in,f1+1,f1+m-f2,f2,m-1);
23         if(m<l2)
24             node->right=CBT(pre,in,f1+m-f2+1,l1,m+1,l2);
25         return node;
26     }
27 };