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80 lines
2.2 KiB
Matlab
80 lines
2.2 KiB
Matlab
%ProjectEuler/Octave/Problem14.m
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%Matthew Ellison
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% Created:
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%Modified: 03-28-19
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%This is a script to answer Problem 14 for Project Euler
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%{
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The following iterative sequence is defined for the set of positive integers:
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n → n/2 (n is even)
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n → 3n + 1 (n is odd)
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Which starting number, under one million, produces the longest chain?
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%}
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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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%Setup your variables
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currentLength = 0;
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maxLength = 0;
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currentNum = 1;
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maxNum = 0;
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%Start the timer
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startTime = clock();
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%Step through every number less than 1000000
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while(currentNum < 1000000)
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currentLength = 0;
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workingNum = currentNum; %So you can do math on the current number
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while(workingNum > 1)
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if(mod(workingNum, 2) == 0)
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workingNum = workingNum / 2;
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else
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workingNum = (3 * workingNum) + 1;
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end
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++currentLength;
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end
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%If the current number has a longer chain than the current max it becomes the max
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if(currentLength > maxLength)
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maxLength = currentLength;
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maxNum = currentNum;
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end
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++currentNum;
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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("The longest chain with a starting number < 1000000 is %d with a length of %d\n", maxNum, maxLength)
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printf("It took %f seconds to run this algorithm\n", etime(endTime, startTime))
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%Cleanup the variables
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clear maxLength;
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clear maxNum;
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clear endTime;
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clear startTime;
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clear currentNum;
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clear currentLength;
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clear workingNum;
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clear ans;
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%{
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Results:
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The longest chain with a starting number < 1000000 is 837799 with a length of 524
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It took 1136.180946 seconds to run this algorithm
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%} |