having fun with Hash initializer and the Fibonacci Sequence

fun with Fib.rb

# Having some fun with a simple Fibonacci sequence Hash!

fibonacci = Hash.new {|hash, key| hash[key] = hash[key - 1] + hash[key - 2]}
#=> {}

# Gotta get things started here…

fibonacci[1] = 1
#=> 1

fibonacci[0] = 0
#=> 0

fibonacci[10]
#=> 55

fibonacci
#=> {9=>34, 0=>0, 10=>55, 1=>1, 2=>1, 3=>2, 4=>3, 5=>5, 6=>8, 7=>13, 8=>21}

fibonacci[100]
#=> 354_224_848_179_261_915_075 # underscores added in

fibonacci
# ready for this?
#=> {85=>259695496911122585, 66=>27777890035288, 47=>2971215073, 28=>317811, 9=>34, 95=>31940434634990099905, 76=>3416454622906707, 57=>365435296162, 38=>39088169, 19=>4181, 0=>0, 86=>420196140727489673, 67=>44945570212853, 48=>4807526976, 29=>514229, 10=>55, 96=>51680708854858323072, 77=>5527939700884757, 58=>591286729879, 39=>63245986, 20=>6765, 1=>1, 87=>679891637638612258, 68=>72723460248141, 49=>7778742049, 30=>832040, 11=>89, 97=>83621143489848422977, 78=>8944394323791464, 59=>956722026041, 40=>102334155, 21=>10946, 2=>1, 88=>1100087778366101931, 69=>117669030460994, 50=>12586269025, 31=>1346269, 12=>144, 98=>135301852344706746049, 79=>14472334024676221, 60=>1548008755920, 41=>165580141, 22=>17711, 3=>2, 89=>1779979416004714189, 70=>190392490709135, 51=>20365011074, 32=>2178309, 13=>233, 99=>218922995834555169026, 80=>23416728348467685, 61=>2504730781961, 42=>267914296, 23=>28657, 4=>3, 90=>2880067194370816120, 71=>308061521170129, 52=>32951280099, 33=>3524578, 14=>377, 100=>354224848179261915075, 81=>37889062373143906, 62=>4052739537881, 43=>433494437, 24=>46368, 5=>5, 91=>4660046610375530309, 72=>498454011879264, 53=>53316291173, 34=>5702887, 15=>610, 82=>61305790721611591, 63=>6557470319842, 44=>701408733, 25=>75025, 6=>8, 92=>7540113804746346429, 73=>806515533049393, 54=>86267571272, 35=>9227465, 16=>987, 83=>99194853094755497, 64=>10610209857723, 45=>1134903170, 26=>121393, 7=>13, 93=>12200160415121876738, 74=>1304969544928657, 55=>139583862445, 36=>14930352, 17=>1597, 84=>160500643816367088, 65=>17167680177565, 46=>1836311903, 27=>196418, 8=>21, 94=>19740274219868223167, 75=>2111485077978050, 56=>225851433717, 37=>24157817, 18=>2584}

fibonacci.sort.map(&:last)
#=> [0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987, 1597, 2584, 4181, 6765, 10946, 17711, 28657, 46368, 75025, 121393, 196418, 317811, 514229, 832040, 1346269, 2178309, 3524578, 5702887, 9227465, 14930352, 24157817, 39088169, 63245986, 102334155, 165580141, 267914296, 433494437, 701408733, 1134903170, 1836311903, 2971215073, 4807526976, 7778742049, 12586269025, 20365011074, 32951280099, 53316291173, 86267571272, 139583862445, 225851433717, 365435296162, 591286729879, 956722026041, 1548008755920, 2504730781961, 4052739537881, 6557470319842, 10610209857723, 17167680177565, 27777890035288, 44945570212853, 72723460248141, 117669030460994, 190392490709135, 308061521170129, 498454011879264, 806515533049393, 1304969544928657, 2111485077978050, 3416454622906707, 5527939700884757, 8944394323791464, 14472334024676221, 23416728348467685, 37889062373143906, 61305790721611591, 99194853094755497, 160500643816367088, 259695496911122585, 420196140727489673, 679891637638612258, 1100087778366101931, 1779979416004714189, 2880067194370816120, 4660046610375530309, 7540113804746346429, 12200160415121876738, 19740274219868223167, 31940434634990099905, 51680708854858323072, 83621143489848422977, 135301852344706746049, 218922995834555169026, 354224848179261915075]

# now go impress your friends!