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69 lines
2.4 KiB
Matlab
69 lines
2.4 KiB
Matlab
%ProjectEuler/Octave/Problem20.m
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%Matthew Ellison
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% Created: 03-14-19
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%Modified: 03-28-19
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%What is the sum of the digits of 100!?
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%This project uses the symbolic library. Make sure that you install the symbolic library as well as sympy before running this script
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%The way to do this is run this command in octave: pkg install -forge symbolic
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%This library requires sympy as well. This is easily installed with pip: pip install sympy
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%{
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Copyright (C) 2019 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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pkg load symbolic;
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digits(500) %Keep track of enough digits to do this calculation correctly
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%The number that will hold 100!
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syms num;
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syms x; %A helper that will allow us to do easy math with the symbolics
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num = 1 * x;
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num = subs(num, x, 1);
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%Setup the rest of our variables
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sumOfNums = 0; %Holds the sum of the digits of num
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TOP_NUM = 100; %The number that we are trying to factorial
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%Start the timer
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startTime = clock();
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%Run through every number from 1 to 100 and multiply it by the current number
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for cnt = 1 : TOP_NUM
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num = num * x;
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num = subs(num, x, cnt);
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end
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%Get a string of the numebr because it is easier to pull appart the individual characters for the sum
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numString = char(num);
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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 : size(numString)(2)
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sumOfNums += str2num(numString(cnt));
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end
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%Stop the timer
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endTime = clock();
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%Print the results
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printf("100! = %s\n", numString)
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printf("The sum of the digits is: %d\n", sumOfNums)
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printf("It took %f seconds to run this algorithm\n", etime(endTime, startTime))
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%{
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100! = 93326215443944152681699238856266700490715968264381621468592963895217599993229915608941463976156518286253697920827223758251185210916864000000000000000000000000
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The sum of the digits is: 648
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It took 6.356117 seconds to run this algorithm
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%}
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