[UVa] 10242 - Fourth Point !!

題目網址: http://goo.gl/9feGXR

題意:
(from luckycat)


解 法: 基礎的幾何題目囉。

TAG: Computational Geometry,

注意:

程式碼:

	/**
	* Tittle: 10242 - Fourth Point !!
	* Author: Cheng-Shih, Wong
	* Date: 2015/05/26
	*/
	// include files
	#include <iostream>
	#include <cstdio>
	#include <cstring>
	using namespace std;
	// definitions
	#define FOR(i,a,b) for( int i=(a),_n=(b); i<=_n; ++i )
	#define clr(x,v) memset( x, v, sizeof(x) )
	#define EPS 1e-7
	inline const int dcmp( double x )
	{
	if( x < -EPS ) return -1; return x > EPS;
	}
	struct Point {
	double x, y;
	Point( double _x=0, double _y=0 ):
	x(_x), y(_y) {}
	static bool getPoint( Point &p ) {
	return scanf( "%lf%lf", &p.x, &p.y ) == 2;
	}
	const Point operator+( const Point &op ) const {
	return Point( x+op.x, y+op.y );
	}
	const Point operator-( const Point &op ) const {
	return Point( x-op.x, y-op.y );
	}
	const bool operator==( const Point &op ) const {
	return (!dcmp(op.x-x)&&!dcmp(op.y-y));
	}
	};
	// declarations
	Point a[2], b[2];
	// functions
	// main function
	int main( void )
	{
	// input
	while( Point::getPoint(a[0]) &&
	Point::getPoint(a[1]) &&
	Point::getPoint(b[0]) &&
	Point::getPoint(b[1]) ) {
	// solve
	if( a[0] == b[1] )
	swap( b[0], b[1] );
	else if( a[1] == b[0] )
	swap( a[1], a[0] );
	else if( a[1] == b[1] ) {
	swap( a[0], a[1] );
	swap( b[0], b[1] );
	}
	// output
	printf( "%.3lf %.3lf\n", (a[1]+(b[1]-b[0])).x, (a[1]+(b[1]-b[0])).y );
	}
	return 0;
	}

view raw 10242 - Fourth Point.cpp hosted with ❤ by GitHub