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leetcode - Unique Binary Search Trees II

2013-11-11 22:22  张汉生  阅读(121)  评论(0)    收藏  举报

 

 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     vector <TreeNode *> generateTrees(int min, int max){
13         if (min>max){
14             TreeNode * tmp = NULL;
15             return vector<TreeNode*>(1,tmp);
16         }
17         vector<TreeNode *> rlt;
18         for (int i=min; i<=max; i++){
19             vector<TreeNode*> left_nodes = generateTrees(min, i-1);
20             int lsize = left_nodes.size();
21             vector<TreeNode*> right_nodes = generateTrees(i+1,max);
22             int rsize = right_nodes.size();
23             for (int j=0; j<lsize; j++)
24                 for (int k=0; k<rsize; k++){
25                     TreeNode * node = new TreeNode(i);
26                     node->left = left_nodes[j];
27                     node->right = right_nodes[k];
28                     rlt.push_back(node);
29                 }
30         }
31         return rlt;
32     }
33     vector<TreeNode *> generateTrees(int n) {
34         // IMPORTANT: Please reset any member data you declared, as
35         // the same Solution instance will be reused for each test case.
36         return generateTrees(1,n);
37     }
38 };