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63 lines
2.1 KiB
Lua
63 lines
2.1 KiB
Lua
--ProjectEuler/lua/Problem20.lua
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--Matthew Ellison
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-- Created: 03-14-19
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--Modified: 06-19-20
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--What is the sum of the digits of 100!
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--All of my requires, unless otherwise listed, can be found at https://bitbucket.org/Mattrixwv/luaClasses
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--I used the bigint library from https://github.com/empyreuma/bigint.lua
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--[[
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Copyright (C) 2020 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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local bigint = require("bigint")
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TOP_NUM = 100;
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--Start the timer
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local timer = Stopwatch:create();
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timer:start();
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local num = bigint.new(1); --The number to be generated
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local sum = 0; --The sum of the digits in num
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for cnt = 1, TOP_NUM do
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num = bigint.multiply(num, bigint.new(cnt));
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end
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--Get a string of the number because it is easier to pull appart the individual characters to get the sum
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local numString = bigint.unserialize(num, 's');
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--Run through every character in the string, convert it back to an integer and add it to the running sum
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for cnt = 1, string.len(numString) do
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sum = sum + tonumber(string.sub(numString, cnt, cnt));
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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("100! = " .. numString .. '\n');
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io.write("The sum of the digits is: " .. sum .. '\n');
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io.write("It took " .. timer:getMilliseconds() .. " milliseconds to run this algorithm\n");
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--[[ Results:
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100! = 93326215443944152681699238856266700490715968264381621468592963895217599993229915608941463976156518286253697920827223758251185210916864000000000000000000000000
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The sum of the digits is: 648
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It took 81.113 milliseconds to run this algorithm
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]]
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