递归实现

/** * Definition for binary tree * struct TreeNode { *     int val; *     TreeNode *left; *     TreeNode *right; *     TreeNode(int x) : val(x), left(NULL), right(NULL) {} * }; */class Solution {public:    TreeNode *build( vector
     
      &preorder,vector
      
        &inorder,int start,int end,int start1,int end1)    {        if(start==end)        return NULL;                int i;        TreeNode * tmp = new TreeNode(preorder[start]);                        for(i=start1; i
       
        left=left;        tmp->right=right;        return tmp;            }    TreeNode *buildTree(vector
        
          &preorder, vector
         
           &inorder) {        // Start typing your C/C++ solution below        // DO NOT write int main() function        return build(preorder,inorder,0,preorder.size(),0,inorder.size());    }};