Hashing might help but you have to consider the risk of collisions. If records are all the same size, then seeking for comparisons can be done in linear time, but the hit for actually doing the comparisons will be a function of their how many collisions there are -- and the smaller your hashspace, the more of those there will be.

If you don't know anything about a typical record, I think the mergesort approach is a good shot.

In reply to Re^2: Find duplicate lines from the file and write it into new file. by gaal
in thread Find duplicate lines from the file and write it into new file. by anna_here

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