Difference between revisions of "Euler problems/71 to 80"
BrettGiles (talk | contribs) m (EulerProblems/71 to 80 moved to Euler problems/71 to 80) |
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Solution: |
Solution: |
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<haskell> |
<haskell> |
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− | problem_75 = |
+ | problem_75 = length . filter ((== 1) . length) $ perims |
+ | where perims = group $ sort [scale*p | p <- pTriples, scale <- [1..10^6 `div` p]] |
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+ | pTriples = [p | |
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+ | n <- [1..1000], |
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+ | m <- [n+1..1000], |
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+ | even n || even m, |
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+ | gcd n m == 1, |
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+ | let a = m^2 - n^2, |
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+ | let b = 2*m*n, |
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+ | let c = m^2 + n^2, |
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+ | let p = a + b + c, |
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+ | p <= 10^6] |
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</haskell> |
</haskell> |
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Revision as of 08:35, 30 March 2007
Problem 71
Listing reduced proper fractions in ascending order of size.
Solution:
problem_71 = undefined
Problem 72
How many elements would be contained in the set of reduced proper fractions for d ≤ 1,000,000?
Solution:
problem_72 = undefined
Problem 73
How many fractions lie between 1/3 and 1/2 in a sorted set of reduced proper fractions?
Solution:
problem_73 = undefined
Problem 74
Determine the number of factorial chains that contain exactly sixty non-repeating terms.
Solution:
problem_74 = undefined
Problem 75
Find the number of different lengths of wire can that can form a right angle triangle in only one way.
Solution:
problem_75 = length . filter ((== 1) . length) $ perims
where perims = group $ sort [scale*p | p <- pTriples, scale <- [1..10^6 `div` p]]
pTriples = [p |
n <- [1..1000],
m <- [n+1..1000],
even n || even m,
gcd n m == 1,
let a = m^2 - n^2,
let b = 2*m*n,
let c = m^2 + n^2,
let p = a + b + c,
p <= 10^6]
Problem 76
How many different ways can one hundred be written as a sum of at least two positive integers?
Solution:
problem_76 = undefined
Problem 77
What is the first value which can be written as the sum of primes in over five thousand different ways?
Solution:
problem_77 = undefined
Problem 78
Investigating the number of ways in which coins can be separated into piles.
Solution:
problem_78 = undefined
Problem 79
By analysing a user's login attempts, can you determine the secret numeric passcode?
Solution:
problem_79 = undefined
Problem 80
Calculating the digital sum of the decimal digits of irrational square roots.
Solution:
problem_80 = undefined