2021-07-20 二叉树和为某路径上的值

private ArrayList<ArrayList<Integer>> res;
public ArrayList<ArrayList<Integer>> FindPath(TreeNode root,int target) {
//这不就是树的
res = new ArrayList();
bfs(root,target,new ArrayList<Integer>());
return res;
}

private void bfs(TreeNode root,int target,ArrayList<Integer> ls){
    if(null == root){
        return;
    }
    ls.add(root.val);
    if(root.val == target && null == root.left && null == root.right){
        res.add(new ArrayList<Integer>(ls));
    }
    bfs(root.left,target-root.val,ls);
    bfs(root.right,target - root.val,ls);
    ls.remove(ls.size()-1);
}