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34 lines
1.2 KiB
Markdown
34 lines
1.2 KiB
Markdown
# [257. Binary Tree Paths](https://leetcode.com/problems/binary-tree-paths/description/)
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# 思路
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递归算法，用一个curr_path记录当前的path，每当遇到叶子节点时就将curr_path push到一个字符串数组里。
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# C++
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``` C++
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class Solution {
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private:
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vector<string>res;
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string curr_path;
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void find_leaf(TreeNode* root){
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if(root == NULL) return;
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if(!curr_path.empty()) curr_path += "->"; // 不是第一个数，应该先加上“->”
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curr_path += (to_string(root -> val));
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if(root -> right == NULL && root -> left == NULL) res.push_back(curr_path);
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find_leaf(root -> left);
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find_leaf(root -> right);
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// 将当前节点从curr_path中删掉,注意可能是负数所以不能用“-”作为箭头的标志
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while(!curr_path.empty() && curr_path[curr_path.size()-1] != '>'){ // 删除最后一个字符直到curr_path空了或者遇到箭头的标志">"
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curr_path.erase(curr_path.end() - 1);
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}
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if(!curr_path.empty()) curr_path.erase(curr_path.size() - 2, 2); // 删除末尾的"->"
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}
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public:
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vector<string> binaryTreePaths(TreeNode* root) {
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find_leaf(root);
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return res;
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}
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};
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```
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