编程珠玑习题：包含点的两条直线

 

 

 

 

my @a = qw/1 2 3 4 5/;
my @b = qw/1 2 3 4 5/;
my ($x, $y) = (0.5, 4);

my $start = 0;
my $end = 4;

my $cursor;

while(1){

    last if(($end - $start) == 1);
    $cursor = int(($start+$end)/2);
    my $v = $a[$cursor]*$x + $b[$cursor];

    if($y>$v){
        $start = $cursor;
        next;
    }
    if($y<$v){
        $end = $cursor;
        next;
    }
}
print "Start = $start End = $end \n";