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leetcode - Construct Binary Tree from Preorder and Inorder Traversal

2013-03-26 21:05  张汉生  阅读(155)  评论(0)  编辑  收藏  举报

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 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 * buildTree(vector<int>::iterator inBegin, vector<int>::iterator inEnd, 
13                         vector<int>::iterator preBegin, vector<int>::iterator preEnd){
14         int val = *(preBegin);
15         TreeNode * root = new TreeNode(val);
16         vector<int>::iterator ii, jj;
17         for (ii=inBegin, jj=preBegin+1; ii!=inEnd && *ii!=val; ii++, jj++);
18         if (ii!=inBegin)
19             root->left = buildTree(inBegin, ii, preBegin+1, jj);
20         if (ii+1 != inEnd)
21             root->right = buildTree(ii+1, inEnd, jj, preEnd);
22         return root;
23     }
24     TreeNode *buildTree(vector<int> &preorder, vector<int> &inorder) {
25         // Start typing your C/C++ solution below
26         // DO NOT write int main() function
27         if (inorder.empty())
28             return NULL;
29         return buildTree(inorder.begin(),inorder.end(),preorder.begin(), preorder.end());
30     }
31 };