Iterated digits squaring: Difference between revisions
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(Scala contribution added.) |
(Add Swift) |
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}</lang> |
}</lang> |
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=={{header|Swift}}== |
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{{trans|C}} |
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{{libheader|Attaswift BigInt}} |
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With nth power support. |
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<lang swift>import BigInt |
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func is89(_ n: Int) -> Bool { |
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var n = n |
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while true { |
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var s = 0 |
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repeat { |
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s += (n%10) * (n%10) |
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n /= 10 |
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} while n > 0 |
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if s == 89 { |
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return true |
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} else if s == 1 { |
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return false |
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} |
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n = s |
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} |
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} |
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func iterSquare(upToPower pow: Int) { |
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var sums = [BigInt](repeating: 0, count: pow * 81 + 1) |
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sums[0] = 1 |
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for n in 1...pow { |
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var i = n * 81 |
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while i > 0 { |
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for j in 1..<10 { |
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let s = j * j |
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guard s <= i else { break } |
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sums[i] += sums[i-s] |
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} |
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i -= 1 |
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} |
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var count89 = BigInt(0) |
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for x in 1..<n*81 + 1 { |
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guard is89(x) else { continue } |
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count89 += sums[x] |
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} |
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print("1->10^\(n): \(count89)") |
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} |
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} |
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iterSquare(upToPower: 8)</lang> |
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{{out}} |
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<pre>1->10^1: 7 |
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1->10^2: 80 |
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1->10^3: 857 |
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1->10^4: 8558 |
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1->10^5: 85623 |
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1->10^6: 856929 |
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1->10^7: 8581146 |
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1->10^8: 85744333</pre> |
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=={{header|Tcl}}== |
=={{header|Tcl}}== |
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All three versions below produce identical output (<tt>85744333</tt>), but the third is fastest and the first is the slowest, both by substantial margins. |
All three versions below produce identical output (<tt>85744333</tt>), but the third is fastest and the first is the slowest, both by substantial margins. |
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