CareerCup

public StringBuffer retrieveFromFile()
{
StringBuffer sb = new StringBuffer();
try
{
Pattern pattern = Pattern.compile("b[ [a-z][A-Z][0-9] ]*");
Scanner s = null;
try
{
s = new Scanner(
new BufferedReader(
new FileReader(
"C:\\Users\\skushwaha\\eclipse\\helios\\Algorithms & Java\\src\\com\\questions\\amazon\\UniqueIDs.txt")));
while (s.hasNext())
{
if (s.hasNext(pattern))
{
sb.append(s.next() + "\n");
}
else
{
s.next();
}
}
}
finally
{
if (s != null)
{
s.close();
}
}
}
catch (Exception e)
{
e.printStackTrace();
}
return sb;
}

use a regular expression: ^b[a-zA-Z\d\w]*
create a dictionary
if product ID not null then enter into dictionary if not present
then no test case will fail

use a set
put the product ids starting with b
set doesnt allows duplicate elements