剑指Offer-24.二叉树中和为某一值的路径(C++/Java)

class Solution {
public:
    vector<vector<int> > FindPath(TreeNode* root,int expectNumber) {
        vector<int> v;
        dfs(root, v, expectNumber);
        return res;
    }
    void dfs(TreeNode* root, vector<int> &v, int sum){
        if(root == nullptr)
            return;
        v.push_back(root->val);
        if(root->left == nullptr && root->right == nullptr){
            if(sum == root->val)
                res.push_back(v);
        }
        else{
            dfs(root->left, v, sum-root->val);
            dfs(root->right, v, sum-root->val);
        }
        v.pop_back();
    }
private:
    vector<vector<int>> res;
};

import java.util.ArrayList;
/**
public class TreeNode {
    int val = 0;
    TreeNode left = null;
    TreeNode right = null;

    public TreeNode(int val) {
        this.val = val;

    }

}
*/
public class Solution {
    public ArrayList<ArrayList<Integer>> FindPath(TreeNode root,int target) {
        res = new ArrayList<>();
        ArrayList<Integer> l = new ArrayList<>();
        dfs(root, l, target);
        return res;
    }
    public void dfs(TreeNode root, ArrayList<Integer> l, int sum){
        if(root == null)
            return;
        l.add(root.val);
        if(root.left == null && root.right == null){
            if(root.val == sum){
                res.add(new ArrayList(l));
            }
        }
        else{
            dfs(root.left, l, sum-root.val);
            dfs(root.right, l, sum-root.val);
        }
        l.remove(l.size()-1);
    }
    private ArrayList<ArrayList<Integer>> res;
}