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ProjectEulerOctave/Problem26.m

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2.9 KiB
Matlab

function [] = Problem26()
%ProjectEuler/Octave/Problem26.m
%Matthew Ellison
% Created: 08-02-19
%Modified: 08-02-19
%Find the value of d < 1000 for which 1/d contains the longest recurring cycle in its decimal fraction part.
%{
Copyright (C) 2019 Matthew Ellison
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
%}
TOP_NUMBER = 999; %The largest denominator to the checked
%Setup variables
longestCycle = 0; %
longestNumber = 1;
%Start the timer
startTime = clock();
%Start with 1/2 and find out how long the longest cycle is by checking the remainders
%Loop through every number from 2-999 and use it for the denominator
for denominator = 2 : TOP_NUMBER
remainderList = []; %Holds the list of remainders
endFound = false; %Holds whether we have found an end ot the number (either a cycle or a 0 for a remainder)
cycleFound = false; %Holds whether a cycle was detected
numerator = 1; %The numerator that will be divided
while(~endFound)
%Get the remainder after the division
remainder = mod(numerator, denominator);
%Check if the remainder is 0
%If it is, set the flag
if(remainder == 0)
endFound = true;
%Check if the remainder is in the list
%If it is in the list, set the appropriate flags
elseif(isFound(remainderList, remainder))
endFound = true;
cycleFound = true;
%Else add it to the list
else
remainderList(end + 1) = remainder;
end
%Multiply the remainder by 10 to continue finding the next remainder
numerator = remainder * 10;
end
%If a cycle was found check the size of the list against the largest cycle
if(cycleFound)
%If it is larger than the largest, set it as the new largest
if(size(remainderList)(2) > longestCycle)
longestCycle = size(remainderList)(2);
longestNumber = denominator;
end
end
end
%End the timer
endTime = clock();
%Print the results
printf("The longest cycle is %d digits long\n", longestCycle);
printf("It is started with the number %d\n", longestNumber);
printf("It took %f seconds to run this algorithm\n", etime(endTime, startTime));
end
function [found] = isFound(array, key)
found = false; %Start with a false. It only turns true if you find key in array
for location = 1 : size(array)(2)
if(key == array(location))
found = true;
return;
end
end
end
%{
Results:
The longest cycle is 982 digits long
It is started with the number 983
It took 49.173325 seconds to run this algorithm
%}