算法描述：

Given an integer?n, generate all structurally unique?BST's?(binary search trees) that store values 1 ...?n.

Example:

Input: 3 Output: [[1,null,3,2],[3,2,null,1],[3,1,null,null,2],[2,1,3],[1,null,2,null,3] ] Explanation: The above output corresponds to the 5 unique BST's shown below:1 3 3 2 1\ / / / \ \3 2 1 1 3 2/ / \ \2 1 2 3

解題思路：深度優先，遞歸求解。

vector<TreeNode*> generateTrees(int n) {vector<TreeNode*> resuts;if(n==0) return resuts;return generate(1,n);}vector<TreeNode*> generate(int start, int end){vector<TreeNode*> results;if(start > end){results.push_back(nullptr);return results;}for(int i = start; i <= end; i++){vector<TreeNode*> left = generate(start,i-1);vector<TreeNode*> right = generate(i+1,end);for(auto l:left){for(auto r:right){TreeNode* temp = new TreeNode(i);temp->left = l;temp->right = r;results.push_back(temp);}}}return results;}

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轉載于:https://www.cnblogs.com/nobodywang/p/10348481.html

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