#P11674. [USACO25JAN] Reachable Pairs G
[USACO25JAN] Reachable Pairs G
Description
Consider an undirected graph with nodes labeled and edges (). You're given a binary string . At time for each ,
- If , node is removed from the graph.
- If , node is removed from the graph, and edges are added between every pair of neighbors that node had just before removal.
Note that in both cases, when a node is removed from the graph all of its incident edges are removed as well.
Count the number of pairs of nodes that can reach each other via some sequence of edges just before each of timesteps .
Input Format
The first line contains and .
The second line contains the bit string of length .
The next lines each contain two integers denoting an edge of the graph.
Output Format
lines, the number of pairs before each timestep.
3 2
111
1 2
1 3
3
1
0
3 2
000
1 2
1 3
3
0
0
7 8
1101101
6 2
1 2
2 3
6 3
1 3
1 7
4 5
2 7
11
7
4
2
1
1
0
Hint
For Sample 1:
Before any removals, all pairs of nodes are reachable from each other. After node is removed, an edge is added between and , so they can still reach each other.
For Sample 2:
Before any removals, all pairs of nodes are reachable from each other. After node is removed, and can no longer reach each other.
SCORING:
- Inputs 4-6:
- Inputs 7-8: All equal zero.
- Inputs 9-11: All equal one.
- Inputs 12-23: No additional constraints.
京公网安备 11011102002149号