Submission #2852657


Source Code Expand

#include <iostream>
#include <stdio.h>
#include <math.h>
#define eps 1e-8

using namespace std;

struct vec2d{
	double x, y;
	vec2d(){}
	vec2d(double x, double y){
		this->x = x, this->y = y;
	}
	double add(double a, double b){
		if(fabs(a+b) < eps * (fabs(a) + fabs(b))) return 0.0;
		return a+b;
	}
	vec2d operator+(vec2d ope){
		return vec2d(add(x, ope.x), add(y, ope.y));
	}
	vec2d operator-(vec2d ope){
		return vec2d(add(x, -ope.x), add(y, -ope.y));
	}
	vec2d operator*(double t){
		return vec2d(x*t, y*t);
	}
	vec2d operator/(double t){
		return vec2d(x/t, y/t);
	}
	double dot(vec2d ope){
		return add(x*ope.x, y*ope.y);
	}
	double cross(vec2d ope){
		return add(x*ope.y, -y*ope.x);
	}
	double norm(){
		double d2 = dot(*this);
		if(d2 > 0) return sqrt(d2);
		return 0.0;
	}
};

double distPP(vec2d p, vec2d q){
	return (p-q).norm();
}

vec2d p[3];

vec2d getcenter(int i, double r)
{
	vec2d a, b;
	a = p[(i+1)%3] - p[i], b = p[(i+2)%3] - p[i];
	double th = acos(a.dot(b) / (a.norm() * b.norm()));
	
	a = a / a.norm();
	if(a.cross(b) < 0) b = vec2d(a.y, -a.x);
	else b = vec2d(-a.y, a.x);
	
	vec2d ret = p[i];
	ret = ret + a * r / tan(th/2);
	ret = ret + b * r;
	return ret;
}

bool check(double r)
{
	vec2d c[3];
	for(int i = 0; i < 3; i++) c[i] = getcenter(i, r);
	return distPP(c[0], c[1]) >= 2*r || distPP(c[1], c[2]) >= 2*r || distPP(c[2], c[0]) >= 2*r;
}

int main(void)
{
	for(int i = 0; i < 3; i++){
		cin >> p[i].x >> p[i].y;
	}
	
	double L = distPP(p[0], p[1]) + distPP(p[1], p[2]) + distPP(p[2], p[0]);
	double S = fabs((p[1]-p[0]).cross(p[2]-p[0]) / 2);
	double R = 2*S/L;
	
	double ub = R, lb = 0, mid;
	for(int i = 0; i < 100; i++){
		mid = (ub + lb) * 0.5;
		if(check(mid)) lb = mid;
		else ub = mid;
	}
	printf("%.11f\n", (ub+lb)*0.5);
	return 0;
}

Submission Info

Submission Time
Task B - Inscribed Bicycle
User leaf1415
Language C++14 (GCC 5.4.1)
Score 500
Code Size 1861 Byte
Status AC
Exec Time 2 ms
Memory 256 KB

Judge Result

Set Name Sample All
Score / Max Score 0 / 0 500 / 500
Status
AC × 2
AC × 18
Set Name Test Cases
Sample example0.txt, example1.txt
All 000.txt, 001.txt, 002.txt, 003.txt, 004.txt, 005.txt, 006.txt, 007.txt, 008.txt, 009.txt, 010.txt, 011.txt, 012.txt, 013.txt, 014.txt, 015.txt, example0.txt, example1.txt
Case Name Status Exec Time Memory
000.txt AC 1 ms 256 KB
001.txt AC 1 ms 256 KB
002.txt AC 1 ms 256 KB
003.txt AC 1 ms 256 KB
004.txt AC 1 ms 256 KB
005.txt AC 1 ms 256 KB
006.txt AC 1 ms 256 KB
007.txt AC 1 ms 256 KB
008.txt AC 1 ms 256 KB
009.txt AC 1 ms 256 KB
010.txt AC 2 ms 256 KB
011.txt AC 1 ms 256 KB
012.txt AC 1 ms 256 KB
013.txt AC 1 ms 256 KB
014.txt AC 1 ms 256 KB
015.txt AC 1 ms 256 KB
example0.txt AC 1 ms 256 KB
example1.txt AC 1 ms 256 KB