2021-10-30 04:25:12 +08:00
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--[[
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MIT License
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Copyright (c) 2017 Gabriel de Quadros Ligneul
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in all
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copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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]]
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-- The Computer Language Benchmarks Game
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-- http://benchmarksgame.alioth.debian.org/
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-- contributed by Mike Pall
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2023-12-05 04:48:31 +08:00
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local function prequire(name) local success, result = pcall(require, name); return if success then result else nil end
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local bench = script and require(script.Parent.bench_support) or prequire("bench_support") or require("../../bench_support")
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2021-10-30 04:25:12 +08:00
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function test()
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local function fannkuch(n)
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local p, q, s, sign, maxflips, sum = {}, {}, {}, 1, 0, 0
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for i=1,n do p[i] = i; q[i] = i; s[i] = i end
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repeat
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-- Copy and flip.
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local q1 = p[1] -- Cache 1st element.
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if q1 ~= 1 then
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for i=2,n do q[i] = p[i] end -- Work on a copy.
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local flips = 1
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repeat
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local qq = q[q1]
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if qq == 1 then -- ... until 1st element is 1.
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sum = sum + sign*flips
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if flips > maxflips then maxflips = flips end -- New maximum?
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break
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end
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q[q1] = q1
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if q1 >= 4 then
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local i, j = 2, q1 - 1
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repeat q[i], q[j] = q[j], q[i]; i = i + 1; j = j - 1; until i >= j
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end
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q1 = qq; flips = flips + 1
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until false
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end
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if sign == 1 then
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p[2], p[1] = p[1], p[2]; sign = -1 -- Rotate 1<-2.
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else
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p[2], p[3] = p[3], p[2]; sign = 1 -- Rotate 1<-2 and 1<-2<-3.
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for i=3,n do
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local sx = s[i]
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if sx ~= 1 then s[i] = sx-1; break end
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if i == n then return sum, maxflips end -- Out of permutations.
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s[i] = i
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-- Rotate 1<-...<-i+1.
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local t = p[1]; for j=1,i do p[j] = p[j+1] end; p[i+1] = t
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end
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end
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until false
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end
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local n = tonumber(arg and arg[1]) or 8
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local sum, flips = fannkuch(n)
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print(sum, "\nPfannkuchen(", n, ") = ", flips, "\n")
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end
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bench.runCode(test, "fannkuchen-redux")
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