77 lines
2.2 KiB
Lua
77 lines
2.2 KiB
Lua
--[[
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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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local bench = script and require(script.Parent.bench_support) or require("bench_support")
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function test()
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local N = tonumber((arg and arg[1]) or 8) -- board size
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-- check whether position (n,c) is free from attacks
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local function isplaceok (a, n, c)
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for i = 1, n - 1 do -- for each queen already placed
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if (a[i] == c) or -- same column?
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(a[i] - i == c - n) or -- same diagonal?
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(a[i] + i == c + n) then -- same diagonal?
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return false -- place can be attacked
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end
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end
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return true -- no attacks; place is OK
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end
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-- print a board
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local function printsolution (a)
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for i = 1, N do
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for j = 1, N do
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--print(a[i] == j and "X" or "-", " ")
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end
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--print("\n")
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end
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--print("\n")
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end
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-- add to board 'a' all queens from 'n' to 'N'
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local function addqueen (a, n)
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if n > N then -- all queens have been placed?
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printsolution(a)
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else -- try to place n-th queen
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for c = 1, N do
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if isplaceok(a, n, c) then
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a[n] = c -- place n-th queen at column 'c'
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addqueen(a, n + 1)
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end
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end
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end
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end
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-- run the program
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addqueen({}, 1)
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end
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bench.runCode(test, "queen")
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