#P3109. [USACO14OPEN] Code Breaking G
[USACO14OPEN] Code Breaking G
Description
The cows keep getting in trouble by taking rides on Farmer John's tractor, so he has hidden the keys to the tractor in a fancy new safe in his office. Undeterred, the cows have vowed to try and break into this safe.
The safe is protected by a rather complicated passcode system. The passcode entry system is arranged as a rooted tree of nodes, each of which requires a digit between and . The nodes are indexed .
The only information that the cows have is that certain sequences of length do not occur along particular paths upwards through the tree.
Given length- sequences, together with their starting nodes in the tree, help the cows figure out how many passcodes have been ruled out. You should compute your answer modulo .
Input Format
Line : Two space-separated integers, and .
Lines : Line contains a single integer , denoting the parent of node i in the tree .
Lines : Line describes the ith sequence known not to occur in the code. The line will contain and separated by a space, where is the starting node of the sequence, and is a -digit string known not to occur starting at and proceeding upward in the tree. It is guaranteed that the root is at least steps upward from .
Output Format
Line : A single integer giving the number of ruled-out configurations,modulo .
6 2
0
1
2
3
3
4 01234
5 91234
19
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