-
Notifications
You must be signed in to change notification settings - Fork 2
/
29.rb
39 lines (37 loc) · 879 Bytes
/
29.rb
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
# Problem 29
# 25 October 2002
#
# Consider all integer combinations of a^b for 2 <= a <= 5 and 2 <= b <= 5:
#
# 2^2=4, 2^3=8, 2^4=16, 2^5=32
# 3^2=9, 3^3=27, 3^4=81, 3^5=243
# 4^2=16, 4^3=64, 4^4=256, 4^5=1024
# 5^2=25, 5^3=125, 5^4=625, 5^5=3125
#
# If they are then placed in numerical order, with any repeats removed, we get
# the following sequence of 15 distinct terms:
#
# 4, 8, 9, 16, 25, 27, 32, 64, 81, 125, 243, 256, 625, 1024, 3125
#
# How many distinct terms are in the sequence generated by a^b for 2 <= a <= 100 and 2 <= b <= 100?
# irb> terms={}
# => {}
# irb> 2.upto(100) do |a|
# ?> 2.upto(100) do |b|
# ?> terms[a**b] = true
# irb> end
# irb> end
# => 2
# irb> terms.size
# => 9183
terms={}
2.upto(100) do |a|
2.upto(100) do |b|
terms[a**b] = true
end
end
puts terms.size
# 9183
# real 0m0.138s
# user 0m0.057s
# sys 0m0.006s