Sword refers to the path of offer acwing 47 in a binary tree that is neutralized to a certain value

Topic

answer

We only need to traverse all the paths, and then find the matching path, pay attention to restore the state after each recursion is completed

Code

/**
 * 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<vector<int>> res;
    vector<int> path;
    
    void dfs(TreeNode *root, int sum) {
    
    
        if (!root) return;
        sum -= root->val;
        path.push_back(root->val);
        if (!root->left && !root->right && !sum) {
    
    
            res.push_back(path);
        }
        dfs(root->left, sum);
        dfs(root->right, sum);
        path.pop_back();  //还原状态
    }
    
    vector<vector<int>> findPath(TreeNode *root, int sum) {
    
    
        dfs(root, sum);
        return res;
    }
};