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| 1 | +/** |
| 2 | + * Definition for a binary tree node. |
| 3 | + * struct TreeNode { |
| 4 | + * int val; |
| 5 | + * TreeNode *left; |
| 6 | + * TreeNode *right; |
| 7 | + * TreeNode() : val(0), left(nullptr), right(nullptr) {} |
| 8 | + * TreeNode(int x) : val(x), left(nullptr), right(nullptr) {} |
| 9 | + * TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {} |
| 10 | + * }; |
| 11 | + */ |
| 12 | +/** |
| 13 | + * Definition for a binary tree node. |
| 14 | + * struct TreeNode { |
| 15 | + * int val; |
| 16 | + * TreeNode *left; |
| 17 | + * TreeNode *right; |
| 18 | + * TreeNode() : val(0), left(nullptr), right(nullptr) {} |
| 19 | + * TreeNode(int x) : val(x), left(nullptr), right(nullptr) {} |
| 20 | + * TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {} |
| 21 | + * }; |
| 22 | + */ |
| 23 | +class Solution { |
| 24 | +public: |
| 25 | + vector<int>ans; |
| 26 | + vector<int> preorderTraversal(TreeNode* root) { |
| 27 | + if(root==nullptr){ |
| 28 | + return {}; |
| 29 | + } |
| 30 | + ans.push_back(root->val); |
| 31 | + preorderTraversal(root->left); |
| 32 | + preorderTraversal(root->right); |
| 33 | + return ans; |
| 34 | + } |
| 35 | +}; |
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