function FindPath(root, expectNumber) {
    let result = []
    if(!root) return result
    dfs(root,expectNumber,[],0,result)
    return result
}
function dfs(root,expectNumber,path,cur,result){
    cur+=root.val
    path.push(root)
    if(cur==expectNumber && root.left==null && root.right==null){
        result.push(path.slice(0))
    }
    if(root.left){
        dfs(root.left,path,expectNumber,cur,result)
    }
    if(root.right){
        dfs(root.left,path,expectNumber,cur,result)
    }
    //弹出最后一个节点 继续dfs
    path.pop()
}