Why are you initializing @collect with NUM_TOSSES + 1 elements?

The idiomatic way to initialize @collect with NUM_TOSSES elements is usually:

my @collect = ( 0 ) x NUM_TOSSES;
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As Eliya points out, 20 tosses could give 21 outcomes as regards the number of "tails" tossed, i.e. 0, 1, ... 19 or 20 so your way should be

my @collect = ( 0 ) x ( NUM_TOSSES + 1 );
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and I would agree that your way is perhaps more idiomatic. However, I felt that

my @collect = map 0, 0 .. NUM_TOSSES;
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better illustrated the relation between the numbers of tosses and outcomes. What do others think?