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binary-tree-paths.cpp
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binary-tree-paths.cpp
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// Time: O(n * h)
// Space: O(h)
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
vector<string> binaryTreePaths(TreeNode* root) {
vector<string> result;
vector<TreeNode *> path;
binaryTreePathsRecu(root, &path, &result);
return result;
}
void binaryTreePathsRecu(TreeNode *node, vector<TreeNode *> *path, vector<string> *result) {
if (!node) {
return;
}
if (!node->left && !node->right) {
string ans = "";
for (const auto& n : *path) {
ans.append(to_string(n->val).append("->"));
}
result->emplace_back(move(ans.append(to_string(node->val))));
}
if (node->left) {
path->emplace_back(node);
binaryTreePathsRecu(node->left, path, result);
path->pop_back();
}
if (node->right) {
path->emplace_back(node);
binaryTreePathsRecu(node->right, path, result);
path->pop_back();
}
}
};