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p030.jl
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p030.jl
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#=
Surprisingly there are only three numbers that can be written as the sum of fourth powers of their digits:
1634 = 14 + 64 + 34 + 44
8208 = 84 + 24 + 04 + 84
9474 = 94 + 44 + 74 + 44
As 1 = 14 is not a sum it is not included.
The sum of these numbers is 1634 + 8208 + 9474 = 19316.
Find the sum of all the numbers that can be written as the sum of fifth powers of their digits.
=#
function sumpow(num, pow)
str = string(num)
result = 0
for i=1:length(str)
result += (parse(Int, str[i]))^pow
end
return result
end
pow = 5
sumnums = 0
# upper limit of numbers that could satisfy num = sumpow(num, pow) is num = pow*9^pow
# i.e. if all the digits are 9s
# ... i think, maybe this needs a closer check
for i=2:pow*9^pow # note: 1 is not included
if i == sumpow(i, pow)
global sumnums += i
end
end
print("the sum of all the numbers that can be written as the sum of {$pow}th powers of their digits is: $sumnums")