LeetCode[Tree]: Path Sum II

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Given a binary tree and a sum, find all root-to-leaf paths where each path’s sum equals the given sum.
For example:
Given the below binary tree and sum = 22,

return

这个题目适合用递归来解，我的C++代码实现如下：

class Solution {public:    vector<vector<int> > pathSum(TreeNode *root, int sum) {        vector<vector<int> > paths;        vector<int> curr_path;        if (!root) return paths;        find(root, sum, paths, curr_path);        return paths;    }private:    void find(TreeNode *root, int sum, vector<vector<int> > &paths, vector<int> &curr_path) {        curr_path.push_back(root->val);        if (root->left == nullptr && root->right == nullptr)            if (root->val == sum) paths.push_back(curr_path);        if (root->left) {            find(root->left, sum - root->val, paths, curr_path);            curr_path.pop_back();        }        if (root->right) {            find(root->right, sum - root->val, paths, curr_path);            curr_path.pop_back();        }    }};

时间性能如下图所示：

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