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- #!/usr/bin/ruby
- # Author: Trizen
- # Date: 18 March 2023
- # https://github.com/trizen
- # https://projecteuler.net/problem=30
- # Runtime: 11.792s
- # The limit can be found by solving for `k` in the inequality:
- # 10^k > k * 9^5
- var k = bsearch_inverse(0, 10, {|k|
- 10**k <=> k*9**5
- })
- say (2 .. 10**k -> lazy.grep {|n| n.digits.sum_by { .ipow(5) } == n }.sum)
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