NOIP '18 P6 - Defending the Kingdom
View as PDFGiven a tree with  vertices such that each vertex has an associated cost 
. There are 
 queries: if vertex 
 must or must not be chosen and vertex 
 must or must not be chosen, what is the minimum cost of a vertex cover (i.e. minimum cost to choose a subset of vertices such that for all edges at least one endpoint is in the subset). If vertex covers do not exist under the constraint given in a query, output 
-1.
Input Specification
The first line contains two integers  and one string 
. 
 represents the number of vertices, 
 represents the number of queries, and
 represents additional constraints satisfied by the test case.
The second line contains  integers 
 denoting the cost associated with vertex 
.
In the following  lines, each line contains two integers 
 denoting there exists an edge 
 in the tree.
In the following  lines, each line contains 4 integers 
 
. If 
, then vertex 
 cannot be included in the vertex cover, while if 
 vertex 
 must be in the vertex cover. Similarly, if 
, vertex 
 cannot be included in the vertex cover, while if 
, vertex 
 must be in the vertex cover.
Output Specification
The output consists of  lines. Each line contains an integer: the 
-th line denotes the minimum cost of a vertex cover satisfying the constraints outlined in the 
-th query. If it is impossible to have a vertex cover satisfying the constraint, output 
-1.
Sample Input 1
5 3 C3
2 4 1 3 9
1 5
5 2
5 3
3 4
1 0 3 0
2 1 3 1
1 0 5 0
Sample Output 1
12
7
-1
For the first query, the subset of vertices shall be .
For the second query, the subset of vertices shall be .
The constraints in the last query cannot be satisfied since both endpoints of edge  cannot be in the vertex cover.
Additional Samples
Additional samples can be found here.
Constraints
For all test cases, , 
.
| Test Case | Type | ||
|---|---|---|---|
| 1-2 | A3 | ||
| 3-4 | C3 | ||
| 5-6 | A3 | ||
| 7 | C3 | ||
| 8-9 | A3 | ||
| 10-11 | C3 | ||
| 12-13 | A1 | ||
| 14-16 | A2 | ||
| 17 | A3 | ||
| 18-19 | B1 | ||
| 20-21 | C1 | ||
| 22 | C2 | ||
| 23-25 | C3 | 
Interpretation of :
A - vertex
and
are connected directly by an edge.
B - if the tree's root is vertex
, then the depth is at most
.
C - no additional constraints on the tree.
1 - for all queries,
,
(i.e. vertex
must be included). There are no constraints on
and
.
2 - in a query, vertex
and
are guaranteed to be adjacent.
3 - no additional constraints on the queries.
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