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generateTrees.cpp
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generateTrees.cpp
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/**
* Definition for binary tree
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
void dfs(int st,int ed,vector<TreeNode *> &res){
if (st>ed){
res.push_back(NULL);
}else{
for (int i=st;i<=ed;i++){
vector<TreeNode *> lefts;
dfs(st,i-1,lefts);
vector<TreeNode *> rights;
dfs(i+1,ed,rights);
for (int li = 0; li<lefts.size();li++) {
for (int ri =0; ri<rights.size();ri++){
TreeNode* node = new TreeNode(i);
node->left=lefts[li];
node->right=rights[ri];
res.push_back(node);
}
}
}
}
}
vector<TreeNode *> generateTrees(int n) {
// Start typing your C/C++ solution below
// DO NOT write int main() function
vector<TreeNode*> res;
dfs(1,n,res);
return res;
}
};