Megacity

Megacity.cpp

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>

using namespace std;

#define EPS 1e-7

const int dcmp( const double x )
{
	if( x < -EPS ) return -1;
	return x > EPS;
}

struct Point {
	double x, y;
	int p;
	double d;

	Point( double _x = 0, double _y = 0, int _p = 0, double _d = 0 ):
		x(_x), y(_y), p(_p), d(_d) {}

	const bool operator<( const Point &op ) const { return ( dcmp(op.d-d) >= 0 ); }
};

int n, ppl;
Point city[1005];

int main( void )
{
	int i;

	while( scanf( "%d%d", &n, &ppl ) == 2 ) {
		for( i = 0; i < n; ++i ) {
			scanf( "%lf%lf%d", &city[i].x, &city[i].y, &city[i].p );
			city[i].d = sqrt( city[i].x*city[i].x+city[i].y*city[i].y );
		}

		sort( city, city+n );

		for( i = 0; i < n && ppl < 1e6; ++i ) {
			ppl += city[i].p;
		}

		if( i == n && ppl < 1e6 ) puts("-1");
		else printf( "%.7lf\n", city[i-1].d );
	}

	return 0;
}