39 lines
1.3 KiB
Nim
39 lines
1.3 KiB
Nim
import bigints, math, sequtils, times
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iterator nodups_hamming(): BigInt =
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var
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m = newSeq[BigInt](1) # give it two values so doubling size works
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h = newSeq[BigInt](1) # reasonably size
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x5 = initBigInt 5
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mrg = initBigInt 3
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x53 = initBigInt 9 # already advanced one step
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x532 = initBigInt 2
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ih, jm, i, j = 0
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yield initBigInt 1 # trivial case of 1
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while true:
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let cph = h.len # move in-place to avoid allocation
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if i >= cph div 2: # move in-place to avoid allocation
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var s = i; var d = 0
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while s < ih: shallowCopy(h[d], h[s]); s += 1; d += 1
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ih -= i; i = 0
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if i >= cph div 2: moveMem(h[0].unsafeAddr,
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h[i].unsafeAddr,
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(ih - i) * h[i].sizeof); ih -= i; i = 0
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if ih >= cph: h.setLen(2 * cph)
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if x532 < mrg: h[ih] = x532; x532 = h[i] * 2; i += 1
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else:
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h[ih] = mrg
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let cpm = m.len
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if j >= cpm div 2: # move in-place to avoid allocation
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var s = j; var d = 0
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while s < jm: shallowCopy(m[d], m[s]); s += 1; d += 1
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jm -= j; j = 0
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if jm >= cpm: m.setLen(2 * cpm)
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if x53 < x5: mrg = x53; x53 = m[j] * 3; j += 1
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else: mrg = x5; x5 = x5 * 5
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m[jm] = mrg
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jm += 1
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ih += 1
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yield h[ih - 1]
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