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Initial commit. Tool works already :)

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Joshua Moerman 2013-09-23 23:17:09 +02:00
commit 17b68d59cf
4 changed files with 102 additions and 0 deletions

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Makefile Normal file
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fourier : main.cpp
$(CXX) $(CXXFLAGS) -Ofast -Wall main.cpp -o fourier

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README.md Normal file
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Fourier Transform
=================
This tool was inspired by the following comic:
![Explanation of the Fourier transform](http://www.smbc-comics.com/comics/20130201.gif)
The comic was right about 624 being the fouriest in base 5, however 625 is fouriest in both base 12 and 23! Amazing!

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{
"folders":
[
{
"path": "/Users/joshua/Documents/Code/fourier-transform"
}
]
}

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main.cpp Normal file
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/*
Calculates the optimal fourier transform(s) for a number
Also outputs distribution of least-fouerist-base
Inspired by http://www.smbc-comics.com/?id=2874
A very naive implementation :)
*/
#include <map>
#include <vector>
#include <iomanip>
#include <iostream>
#include <algorithm>
#include <iterator>
using namespace std;
int length(int number, int base){
int length = 1;
int acc = base;
while(number >= acc){
length++;
acc *= base;
}
return length;
}
int fours(int number, int base){
int count = (number % base) == 4;
while(number > base){
number /= base;
if(number % base == 4) count++;
}
return count;
}
// Performs a fourier transform to make the input fourier
// Done with a linear search, there are probably betters ways
// There is not always a unique base in which the input is fouriest, so we output a vector
vector<int> fourier(int input){
int base = 1;
int current_best = 0;
vector<int> bests{};
do {
base++;
int current = fours(input, base);
if(current >= current_best){
if(current > current_best){
bests.clear();
current_best = current;
}
bests.push_back(base);
}
} while(length(input, base) > 1);
return bests;
}
// The input number is shown, then the fouriness, then the bases in which the input is fouriest.
int main(){
map<int, int> distribution;
cout << "Number, \t Fouriness, \t Possible bases" << endl;
for(int i = 1; i < 1000; i++){
auto bases = fourier(i);
auto nfours = fours(i, bases.back());
distribution[bases.front()]++;
cout << setw(5) << i << ", \t" << setw(5) << nfours << ", \t[ ";
copy(begin(bases), end(bases), ostream_iterator<int>(cout, " "));
cout << "]" << endl;
}
cout << "\nDistribution of least bases" << endl;
for(auto x : distribution){
cout << x.first << ", \t" << x.second << endl;
}
}