A3: pythagorean

 4. find out pythagorean triplets in an integer array.

 

#include <iostream>
#include <vector>
#include <set>
#include <cmath>
using namespace std;

vector<vector<int> > findP( vector<int> & x ) {
	

	set<int> pool;
	vector<vector<int> > rel;
	if(x.size() < 3) return rel;
	
	for( int i=0; i<x.size(); i++) {
		pool.insert( x[i] * x[i]);
	}

	set<int>::const_iterator it1 = pool.begin();
	set<int>::const_iterator it2;// = pool.begin();
	set<int>::const_iterator it3;

	cout<<"pool size: "<<pool.size()<<endl;
	for( ; it1!=pool.end(); it1++) {
		for(it2=++it1; it2!=pool.end();it2++) {
			int temp = *it1 + *it2;
			if( (it3=pool.find(temp)) != pool.end()) {
				vector<int> t;
				t.push_back( (int)(sqrt((double)*it1)));
				t.push_back( (int)(sqrt((double)*it2)));
				t.push_back( (int)(sqrt((double)*it3)));
				rel.push_back( t );
			}
		}
	}
	return rel;
}

int main(int argc, char** argv)
{
	int x[] = {1,3,3,4,7,5,12,13};

	vector<int> input(x,x + sizeof(x)/sizeof(int) );
	vector<vector<int> > rel = findP(input);

	vector<vector<int> >::iterator it;
	for( it=rel.begin(); it!=rel.end(); it++) {
		for( int i=0; i<(*it).size(); i++) {
			cout<<(*it)[i]<<", ";
		}
		cout<<endl;
	}
}