OPTIMIZING THE JAVA VIRTUAL MACHINE INSTRUCTION SET BY ...

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Algorithm NonOverlappingScore(node n)
ChildPositions: an array of pointers to arrays
Retval: a pointer to a list of values to return to the calling function
If n.NumChildren == 0 // it’s a leaf node
Allocate Retval with size 1
Retval[0] = n.StringDepth
Return Retval
End If
For i = 0 to n.NumChildren - 1
ChildPositions[i] = NonOverlappingScore(n.Child[i])
End For
Retval = MultiWayMerge(ChildPositions,n.NumChildren)
For i = 0 to n.NumChildren - 1
Deallocate ChildPositions[i]
End For
n.Score = CountUniqueOccurrences(Retval,n.StringDepth) * n.StringDepth;
Return Retval
Figure 9.5: Algorithm NonOverlappingScore
this shortcoming because the algorithm presented to this point will over estimate
the value of some strings. An extension to the algorithm is presented that shows
how overlapping occurrences of candidate strings can be detected and removed from
consideration.
Two occurrences of a substring of s, denoted by w, are known to overlap if the
absolute value of the difference in their starting positions within s is less than |w|.
It is possible to annotate each interior node in the tree with the score based on the
number of non-overlapping occurrences of the substring represented by the node. This
is accomplished using a depth first traversal of the tree using the algorithm shown in
Figure 9.5.
The algorithm presented in Figure 9.5 makes use of a MultiWayMerge operation.
Greene presents an algorithm that is capable of merging y sorted sequences of total
length x in O(x log y) time [52]. In this algorithm, the total length of all of the