5.If
the middle item is less than quarry, then quarry
should be in the second half of the
list of possible items. So
the subscript of quarry must
lie between middle +1 and last. That is, the
new value of first is middle +1.
6.Repeat
Steps 2 through 5 until quarry is found
or until the halving process uses up the entire list. (When the entire list has been used up, first
> last.) In the second case, quarry was not
in the original list.
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