113.路径总和-ii 剑指 offer 34.cpp

/*
 * @lc app=leetcode.cn id=113 lang=cpp
 *
 * [113] 路径总和 II
 */
// LeetCode 官方方法 1 DFS
// @lc code=start
/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
  public:
    vector<vector<int>> ret;
    vector<int> path;

    void dfs(TreeNode *root, int targetSum) {
        if (root == nullptr) {
            return;
        }
        path.emplace_back(root->val);
        targetSum -= root->val;
        if (root->left == nullptr && root->right == nullptr && targetSum == 0) {
            ret.emplace_back(path);
        }
        dfs(root->left, targetSum);
        dfs(root->right, targetSum);
        path.pop_back();
    }

    vector<vector<int>> pathSum(TreeNode *root, int targetSum) {
        dfs(root, targetSum);
        return ret;
    }
};

// @lc code=end