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81 lines
2.5 KiB
Lua
81 lines
2.5 KiB
Lua
--ProjectEuler/ProjectEulerLua/Problem38.lua
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--Matthew Ellison
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-- Created: 10-11-21
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--Modified: 10-11-21
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--What is the largest 1-9 pandigital number that can be formed as the concatenated product of an integer with 1, 2, ... n where n > 1
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--All of my requires, unless otherwise listed, can be found at https://bitbucket.org/Mattrixwv/luaClasses
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--[[
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Copyright (C) 2021 Matthew Ellison
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program. If not, see <https://www.gnu.org/licenses/>.
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]]
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require "Stopwatch"
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require "Algorithms"
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--Setup the variables
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local timer = Stopwatch:create();
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local HIGHEST_POSSIBLE_NUM = 9999; --The highest number that needs to be checked for a 1-9 pandigital
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local largestNum = 0; --The number passed to the executeFormula function that returns the largest pandigital
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local pandigital = 0; --The largest pandigital number found
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--Functions
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--Take the number ad add its multiples to a string to return
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local function executeFormula(num)
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--Turn the current number into a string
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local numStr = tostring(num);
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numStr = numStr .. tostring(num * 2);
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--Multiply the number and append the product to the string until you have one long enough
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local cnt = 3;
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while(#numStr < 9) do
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numStr = numStr .. tostring(num * cnt);
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cnt = cnt + 1;
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end
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return numStr;
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end
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--Start the timer
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timer:start();
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--Loop from 1 -> HIGHEST_POSSIBLE_NUM checking for pandigitals
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for cnt = 1, HIGHEST_POSSIBLE_NUM do
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--Get the string from the formula
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local numStr = executeFormula(cnt);
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local panNum = tonumber(numStr);
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--If the number is pandigital save it as the highest number
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if(isPandigital(numStr) and (panNum > pandigital)) then
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largestNum = cnt;
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pandigital = panNum;
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end
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end
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--Stop the timer
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timer:stop();
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--Print the results
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io.write("The largest appened product pandigital is " .. pandigital .. "\n");
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io.write("It took " .. timer:getString() .. " to run this algorithm\n");
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--[[ Results:
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The largest appened product pandigital is 932718654
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It took 14.555 milliseconds to run this algorithm
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]]
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