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•

Greenbank

Jolly good.

Finally redid today's properly (rather than the hack to just get the answers).

Day 9 part 2 induced the usual paranoia that the O(n) sliding window algorithm doesn't work (it does as long as you don't have any negative numbers).

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lf in reply to @Greenbank

Now i've just read up on that algorithm and want to attempt it. Should really just do some work though

•

Greenbank in reply to @lf

Here was my part two, @nos is the array of input integers:-

sub part2 {
        my ( $n ) = @_;
        my $s=0;
        my $e=0;
        my $t=$nos[$s];
        while( $s < scalar( @nos ) ) {
                if( $t > $n ) { # Running total is too big, remove first number from current window
                        $t-=$nos[$s];
                        $s++;
                }
                if( $t < $n && $e < scalar( @nos )-1 ) {        # Running total too small, add another number on the end
                        $e++;
                        $t+=$nos[$e];
                }
                if( $s != $e && $t == $n ) {    # Got it, find min and max of current window
                        my $min=$nos[$s];
                        my $max=$nos[$s];
                        for my $ct ( $s..$e ) {
                                $min=$nos[$ct] if( $min > $nos[$ct] );
                                $max=$nos[$ct] if( $max < $nos[$ct] );
                        }
                        return( $min+$max );
                }
        }
}

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