A16235 | Standard Graph Problem
时间限制1s
内存限制256MB
通过 / 提交0/0
题目描述
You are given a weighted directed graph with $n$ vertices and $m$ edges. Each vertex in the graph can be either highlighted or normal. Initially, all vertices are normal. The cost of the graph is defined as the minimum sum of edge weights that need to be selected so that from each normal vertex one can reach at least one highlighted vertex using the selected edges only. If it is not possible to select the edges, the cost is $-1$ instead.
Your task is to compute the cost of the graph after each of the $q$ queries. The queries can be of two types:
- $+\;v_i$ makes vertex $v_i$ highlighted; it is guaranteed that the vertex is normal before the query.
- $-\;v_i$ makes vertex $v_i$ normal; it is guaranteed that the vertex is highlighted before the query.
Output the cost of the graph after each of the $q$ queries.
Your task is to compute the cost of the graph after each of the $q$ queries. The queries can be of two types:
- $+\;v_i$ makes vertex $v_i$ highlighted; it is guaranteed that the vertex is normal before the query.
- $-\;v_i$ makes vertex $v_i$ normal; it is guaranteed that the vertex is highlighted before the query.
Output the cost of the graph after each of the $q$ queries.
输入格式
The first line contains three integers $n$ , $m$ , and $q$ ( $3 \le n \le 2 \cdot 10^5, 1 \le m, q \le 2 \cdot 10^5$ ) — the number of vertices in the graph, the number of edges, and the number of queries.
The next $m$ lines contain the edges of the graph, one edge per line. The $i$ -th line contains three integers $u_i$ , $v_i$ , and $c_i$ ( $1 \leq u_i, v_i \leq n, u_i \ne v_i, 1 \leq c_i \leq 10^6$ ) — the endpoints of the $i$ -th edge (from $u_i$ to $v_i$ ) and its weight ( $c_i$ ).
The next $q$ lines contain the queries, one query per line. The $i$ -th line contains $+\;v_i$ , if it is a query of the first type, and $-\;v_i$ , if it is a query of the second type ( $1 \leq v_i \leq n$ ).
The next $m$ lines contain the edges of the graph, one edge per line. The $i$ -th line contains three integers $u_i$ , $v_i$ , and $c_i$ ( $1 \leq u_i, v_i \leq n, u_i \ne v_i, 1 \leq c_i \leq 10^6$ ) — the endpoints of the $i$ -th edge (from $u_i$ to $v_i$ ) and its weight ( $c_i$ ).
The next $q$ lines contain the queries, one query per line. The $i$ -th line contains $+\;v_i$ , if it is a query of the first type, and $-\;v_i$ , if it is a query of the second type ( $1 \leq v_i \leq n$ ).
输出格式
Output $q$ numbers. The $i$ -th number is the cost of the graph after the first $i$ queries.
输入输出样例
输入 #1
4 5 6 1 2 1 2 3 5 3 2 3 4 1 8 2 1 4 + 1 - 1 + 3 + 1 + 4 + 2
输出 #1
15 -1 14 12 4 0
输入 #2
10 14 10 8 6 4 2 5 1 3 5 4 1 6 3 1 3 7 7 2 1 6 1 3 4 10 1 4 6 5 5 4 1 5 8 10 10 9 1 9 5 1 9 7 6 + 7 + 8 - 7 + 10 + 2 - 10 + 5 - 2 - 5 + 3
输出 #2
28 24 29 19 18 24 18 19 29 20
In the first test:
- After the first query, it is most profitable to select the edges with numbers $3, 4, 5$ , their total cost is $15$ .
- After the second query, there are no highlighted vertices, which means that there are no suitable sets of edges, the cost of the graph is $-1$ .
- After the third query, it is most profitable to select the edges with numbers $1, 2, 5$ , their total cost is $14$ .
- After the fourth query, it is most profitable to select the edges with numbers $4$ and $5$ , their total cost is $12$ .
- After the fifth query, it is most profitable to select only edge number $5$ , its cost is $4$ .
- After the sixth query, all vertices are highlighted and there is no need to select any edges, the cost of the graph is $0$ .
- After the first query, it is most profitable to select the edges with numbers $3, 4, 5$ , their total cost is $15$ .
- After the second query, there are no highlighted vertices, which means that there are no suitable sets of edges, the cost of the graph is $-1$ .
- After the third query, it is most profitable to select the edges with numbers $1, 2, 5$ , their total cost is $14$ .
- After the fourth query, it is most profitable to select the edges with numbers $4$ and $5$ , their total cost is $12$ .
- After the fifth query, it is most profitable to select only edge number $5$ , its cost is $4$ .
- After the sixth query, all vertices are highlighted and there is no need to select any edges, the cost of the graph is $0$ .
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