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100 lines
2.8 KiB
Matlab
100 lines
2.8 KiB
Matlab
function [] = Problem38()
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%ProjectEuler/Octave/Problem38.m
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%Matthew Ellison
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% Created: 10-12-21
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%Modified: 10-12-21
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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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%{
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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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%Start the timer
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startTime = clock();
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%Setup the variables
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HIGHEST_POSSIBLE_NUM = 9999; %The highest number that needs to be checked for a 1-9 pandigital
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largestNum = 0; %The number passed to the executeFormula function that returns the largest pandigital
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pandigital = 0; %The largest pandigital number found
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%Loop from 1 -> HIGHEST_POSSIBLE_NUM checking for pandigitals
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for cnt = 1 : HIGHEST_POSSIBLE_NUM
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%Get the string from the formula
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numStr = executeFormula(cnt);
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panNum = str2num(numStr);
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%If the number is pandigital save it as the highest number
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if(isPandigital(numStr) && (panNum > pandigital))
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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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endTime = clock();
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%Print the results
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printf("The largest appened product pandigital is %d\n", pandigital)
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printf("It took %f seconds to run this algorithm\n", etime(endTime, startTime))
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end
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function [numStr] = executeFormula(num)
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%Turn the current number into a string
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numStr = num2str(num);
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numStr = strcat(numStr, num2str(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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cnt = 3;
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while(size(numStr)(2) < 9)
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numStr = strcat(numStr, num2str(num * cnt));
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cnt += 1;
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end
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end
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function [isPan] = isPandigital(str)
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top = 9;
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bottom = 1;
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isPan = false;
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%Return false if top < bottom
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if(top < bottom)
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return;
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end
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%Return false if the wrong number of characters are in the string
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if(size(str)(2) != (top - bottom + 1))
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return
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end
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%Make sure that all of the needed characters are in the string exactly one time
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for cnt = bottom : top
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if(size(strfind(str, num2str(cnt)))(2) != 1)
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return;
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end
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end
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%If the function has reched this part it has passed all of the falsifying tests
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isPan = true;
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end
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%{
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Results:
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The largest appened product pandigital is 932718654
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It took 13.246925 seconds to run this algorithm
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%}
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