A10532 | Break Up
时间限制1s
内存限制256MB
通过 / 提交0/0
题目描述
Again, there are hard times in Berland! Many towns have such tensions that even civil war is possible.
There are $n$ towns in Reberland, some pairs of which connected by two-way roads. It is not guaranteed that it is possible to reach one town from any other town using these roads.
Towns $s$ and $t$ announce the final break of any relationship and intend to rule out the possibility of moving between them by the roads. Now possibly it is needed to close several roads so that moving from $s$ to $t$ using roads becomes impossible. Each town agrees to spend money on closing no more than one road, therefore, the total number of closed roads will be no more than two.
Help them find set of no more than two roads such that there will be no way between $s$ and $t$ after closing these roads. For each road the budget required for its closure was estimated. Among all sets find such that the total budget for the closure of a set of roads is minimum.
There are $n$ towns in Reberland, some pairs of which connected by two-way roads. It is not guaranteed that it is possible to reach one town from any other town using these roads.
Towns $s$ and $t$ announce the final break of any relationship and intend to rule out the possibility of moving between them by the roads. Now possibly it is needed to close several roads so that moving from $s$ to $t$ using roads becomes impossible. Each town agrees to spend money on closing no more than one road, therefore, the total number of closed roads will be no more than two.
Help them find set of no more than two roads such that there will be no way between $s$ and $t$ after closing these roads. For each road the budget required for its closure was estimated. Among all sets find such that the total budget for the closure of a set of roads is minimum.
输入格式
The first line of the input contains two integers $n$ and $m$ ( $2<=n<=1000$ , $0<=m<=30000$ ) — the number of towns in Berland and the number of roads.
The second line contains integers $s$ and $t$ ( $1<=s,t<=n$ , $s≠t$ ) — indices of towns which break up the relationships.
Then follow $m$ lines, each of them contains three integers $x_{i}$ , $y_{i}$ and $w_{i}$ ( $1<=x_{i},y_{i}<=n$ , $1<=w_{i}<=10^{9}$ ) — indices of towns connected by the $i$ -th road, and the budget on its closure.
All roads are bidirectional. It is allowed that the pair of towns is connected by more than one road. Roads that connect the city to itself are allowed.
The second line contains integers $s$ and $t$ ( $1<=s,t<=n$ , $s≠t$ ) — indices of towns which break up the relationships.
Then follow $m$ lines, each of them contains three integers $x_{i}$ , $y_{i}$ and $w_{i}$ ( $1<=x_{i},y_{i}<=n$ , $1<=w_{i}<=10^{9}$ ) — indices of towns connected by the $i$ -th road, and the budget on its closure.
All roads are bidirectional. It is allowed that the pair of towns is connected by more than one road. Roads that connect the city to itself are allowed.
输出格式
In the first line print the minimum budget required to break up the relations between $s$ and $t$ , if it is allowed to close no more than two roads.
In the second line print the value $c$ ( $0<=c<=2$ ) — the number of roads to be closed in the found solution.
In the third line print in any order $c$ diverse integers from $1$ to $m$ — indices of closed roads. Consider that the roads are numbered from $1$ to $m$ in the order they appear in the input.
If it is impossible to make towns $s$ and $t$ disconnected by removing no more than $2$ roads, the output should contain a single line -1.
If there are several possible answers, you may print any of them.
In the second line print the value $c$ ( $0<=c<=2$ ) — the number of roads to be closed in the found solution.
In the third line print in any order $c$ diverse integers from $1$ to $m$ — indices of closed roads. Consider that the roads are numbered from $1$ to $m$ in the order they appear in the input.
If it is impossible to make towns $s$ and $t$ disconnected by removing no more than $2$ roads, the output should contain a single line -1.
If there are several possible answers, you may print any of them.
输入输出样例
输入 #1
6 7 1 6 2 1 6 2 3 5 3 4 9 4 6 4 4 6 5 4 5 1 3 1 3
输出 #1
8 2 2 7
输入 #2
6 7 1 6 2 3 1 1 2 2 1 3 3 4 5 4 3 6 5 4 6 6 1 5 7
输出 #2
9 2 4 5
输入 #3
5 4 1 5 2 1 3 3 2 1 3 4 4 4 5 2
输出 #3
1 1 2
输入 #4
2 3 1 2 1 2 734458840 1 2 817380027 1 2 304764803
输出 #4
-1
暂无题解
C++ 编辑器
输入
输出
可保存默认模板;新题优先使用已保存模板。
当前快捷键仅展示,暂不支持修改。
- 撤销
Ctrl / ⌘ + Z - 重做
Ctrl / ⌘ + Y - 查找
Ctrl / ⌘ + F - 全选
Ctrl / ⌘ + A - 复制
Ctrl / ⌘ + C - 剪切
Ctrl / ⌘ + X - 粘贴
Ctrl / ⌘ + V - 自动排版
工具栏排版按钮 - 草稿保存
编辑时自动保存到本机
历史
提交记录
状态说明时间源码
AI
作答助手
你好,我是作答助手。可以问思路、复杂度、样例含义或代码报错原因;不会直接给出完整 AC 代码。
确定要清空代码吗?
提交通过
评测结果:Accepted