Java代码

class Solution {
    int s = 0;
    List<List<Integer>> list = new ArrayList<>();
    List<Integer> l = new ArrayList<>();
    public List<List<Integer>> findPath(TreeNode root, int sum) {
        if(root==null)return list;
        dfs(root,sum);
        return list;
    }

    void dfs(TreeNode root,int sum){
        if(root==null)return ;
        s+=root.val;
        l.add(root.val);
        if(root.left==null&&root.right==null&&s==sum){
            list.add(new ArrayList<>(l));
        }
        dfs(root.left,sum);
        dfs(root.right,sum);
        s-=root.val;
        l.remove(l.size()-1);
        return ;
    }

}