【LeetCode】105. 从前序与中序遍历序列构造二叉树

1. class Solution {
2. public:
3.     TreeNode* _buildTree(vector<int>& preorder, vector<int>& inorder,int&previ,int begin,int end) {
4. if(begin>end)
5. return nullptr;
6.         TreeNode*root=new TreeNode(preorder[previ]);
7. int rooti=0;
8. while(preorder[previ]!=inorder[rooti])
9.         {
10.             rooti++;
11.         }
12.         previ++;
13.         root->left=_buildTree(preorder,inorder,previ,begin,rooti-1);
14.         root->right=_buildTree(preorder,inorder,previ,rooti+1,end);
15. return root;
16. }
17. TreeNode* buildTree(vector<int>& preorder, vector<int>& inorder) {
18. int i=0;
19. return _buildTree(preorder,inorder,i,0,inorder.size()-1);
20.     }
21. 
22. };