Leetcode#105 Construct Binary Tree from Preorder and Inorder Traversal

原题地址

基本二叉树操作。

O[       ][              ]

[       ]O[              ]

代码：

 TreeNode *restore(vector<int> &preorder, vector<int> &inorder, int pp, int ip, int len) {
   if (len <= )
     return NULL;

   TreeNode *node = new TreeNode(preorder[pp]);

   if (len == )
     return node;

   int leftLen = ;
   while (inorder[ip + leftLen] != preorder[pp])
     leftLen++;
   node->left = restore(preorder, inorder, pp + , ip, leftLen);
   node->right = restore(preorder, inorder, pp + leftLen + , ip + leftLen + , len - leftLen - );

   return node;
 }

 TreeNode *buildTree(vector<int> &preorder, vector<int> &inorder) {
     return restore(preorder, inorder, , , preorder.size());
 }