找到了，merge中的`t[v].lson = merge(t[v].lson, u);`要改为`t[v].lson = merge(u, t[v].lson);`
by 立柱已选162534 @ 2023-07-25 09:59:45
@[sundyLIUXY](/user/706737)
by 立柱已选162534 @ 2023-07-25 10:13:16
@[立柱已选162534](/user/448545) 大佬orz！！！关注送上qwq
by sundyLIUXY @ 2023-07-25 10:54:03