CF1296F.Berland Beauty
提高+/省选-
通过率:0%
时间限制:3.00s
内存限制:256MB
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题目描述
There are n railway stations in Berland. They are connected to each other by n−1 railway sections. The railway network is connected, i.e. can be represented as an undirected tree.
You have a map of that network, so for each railway section you know which stations it connects.
Each of the n−1 sections has some integer value of the scenery beauty. However, these values are not marked on the map and you don't know them. All these values are from 1 to 106 inclusive.
You asked m passengers some questions: the j-th one told you three values:
- his departure station aj;
- his arrival station bj;
- minimum scenery beauty along the path from aj to bj (the train is moving along the shortest path from aj to bj).
You are planning to update the map and set some value fi on each railway section — the scenery beauty. The passengers' answers should be consistent with these values.
Print any valid set of values f1,f2,…,fn−1, which the passengers' answer is consistent with or report that it doesn't exist.
伯兰有 n 个铁路车站,它们通过 n−1 条铁路线段相互连接。该铁路网络是连通的,即可以表示为一棵无向树。
你拥有一张该网络的地图,因此对每条铁路线段,你都知道它所连接的两个车站。
每条 n−1 条铁路线段均具有某个整数形式的风景优美度值。然而,这些值并未在地图上标出,你并不知晓它们。所有这些值均在 1 到 106(含)之间。
你向 m 名乘客提出了一些问题:第 j 名乘客告诉你以下三个值:
- 他的出发车站 aj;
- 他的到达车站 bj;
- 从 aj 到 bj 的路径上的最小风景优美度(列车沿 aj 到 bj 的最短路径行驶)。
你计划更新地图,在每条铁路线段上设定一个值 fi,表示其风景优美度。乘客的回答必须与这些设定值一致。
请输出任意一组满足乘客回答的合法值 f1,f2,…,fn−1;若不存在这样的取值,则报告无解。
输入格式
The first line contains a single integer n (2≤n≤5000) — the number of railway stations in Berland.
The next n−1 lines contain descriptions of the railway sections: the i-th section description is two integers xi and yi (1≤xi,yi≤n,xi=yi), where xi and yi are the indices of the stations which are connected by the i-th railway section. All the railway sections are bidirected. Each station can be reached from any other station by the railway.
The next line contains a single integer m (1≤m≤5000) — the number of passengers which were asked questions. Then m lines follow, the j-th line contains three integers aj, bj and gj (1≤aj,bj≤n; aj=bj; 1≤gj≤106) — the departure station, the arrival station and the minimum scenery beauty along his path.
第一行包含一个整数 n(2≤n≤5000)—— 表示 Berland 国家中铁路车站的数量。
接下来的 n−1 行描述了铁路线段:第 i 行包含两个整数 xi 和 yi(1≤xi,yi≤n,且 xi=yi),表示第 i 条铁路线段连接的两个车站编号。所有铁路线段均为双向。任意两个车站之间均可通过铁路相互到达。
下一行包含一个整数 m(1≤m≤5000)—— 表示被询问的乘客人数。随后是 m 行,其中第 j 行包含三个整数 aj、bj 和 gj(1≤aj,bj≤n;aj=bj;1≤gj≤106),分别表示该乘客的出发车站、到达车站以及其路径上最小的风景优美度。
输出格式
If there is no answer then print a single integer -1.
Otherwise, print n−1 integers f1,f2,…,fn−1 (1≤fi≤106), where fi is some valid scenery beauty along the i-th railway section.
If there are multiple answers, you can print any of them.
如果没有答案,则输出一个整数 −1。
否则,输出 n−1 个整数 f1,f2,…,fn−1(其中 1≤fi≤106),fi 表示第 i 段铁路沿线的某个合法风景美观度。
如果存在多个答案,输出任意一个即可。
输入输出样例
输入#1
4 1 2 3 2 3 4 2 1 2 5 1 3 3
输出#1
5 3 5
输入#2
6 1 2 1 6 3 1 1 5 4 1 4 6 1 3 3 4 1 6 5 2 1 2 5
输出#2
5 3 1 2 1
输入#3
6 1 2 1 6 3 1 1 5 4 1 4 6 1 1 3 4 3 6 5 3 1 2 4
输出#3
-1
输入解题思路,AI测评打分。不知道怎么写?