Amortization

Another Example: Java Vectors

•

java.util.Vector

–

Intuitively, an expandable

array

–

Operations: addElement(),

elementAt(), setElementAt(),

others

–

addElement() increases the

size of the Vector

•

Implementation: uses arrays

with table doubling

–

When the array gets full,

allocate a new array, twice

as large, and copy all the

data to the new array

•

addElement() can take O(n)

worst-case time

•

Claim: the amortized time

per operation is O(1)

CS409 - Spring 2000

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