基本二叉树操作。
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代码：
1 TreeNode *restore(vector<int> &preorder, vector<int> &inorder, int pp, int ip, int len) { 2 if (len <= 0) 3 return NULL; 4 5 TreeNode *node = new TreeNode(preorder[pp]); 6 7 if (len == 1) 8 return node; 9 10 int leftLen = 0; 11 while (inorder[ip + leftLen] != preorder[pp]) 12 leftLen++; 13 node->left = restore(preorder, inorder, pp + 1, ip, leftLen); 14 node->right = restore(preorder, inorder, pp + leftLen + 1, ip + leftLen + 1, len - leftLen - 1); 15 16 return node; 17 } 18 19 TreeNode *buildTree(vector<int> &preorder, vector<int> &inorder) { 20 return restore(preorder, inorder, 0, 0, preorder.size()); 21 }