HDU-6206 计算几何+大数

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题目

Apple

题解

这道题就是先给你三个点的坐标，再给你一个点的坐标。问这一个点是否在哪三个点构成的圆外，但是要用大数，这里我用的 java 的 BigDecimal。

代码

import java.io.PrintWriter;import java.math.BigDecimal;import java.math.BigInteger;import java.math.MathContext;import java.math.RoundingMode;import java.util.Scanner;class point{    BigDecimal x,y;}public class Main {    private static Boolean judge(point p, point p1, point p2, point p3){        if(p1.y.compareTo(p2.y) == 0 && p2.y.compareTo(p3.y) == 0){            return false;        }        BigDecimal m1,m2,mx1,mx2,my1,my2,xc,yc;        if(p2.y.compareTo(p1.y) == 0){            m2 = p3.x.subtract(p2.x).divide(p3.y.subtract(p2.y)).multiply(new BigDecimal(-1));            mx2 = p2.x.add(p3.x).divide(new BigDecimal(2));            my2 = p2.y.add(p3.y).divide(new BigDecimal(2));            xc = p2.x.add(p1.x).divide(new BigDecimal(2));            yc = m2.multiply(xc.subtract(mx2)).add(my2);        }        else if(p3.y.compareTo(p2.y) == 0){            m1 = p2.x.subtract(p1.x).divide(p2.y.subtract(p1.y)).multiply(new BigDecimal(-1));            mx1 = p1.x.add(p2.x).divide(new BigDecimal(2));            my1 = p1.y.add(p2.y).divide(new BigDecimal(2));            xc = p3.x.add(p2.x).divide(new BigDecimal(2));            yc = m1.multiply(xc.subtract(mx1)).add(my1);        }        else{            m1 = (p2.x.subtract(p1.x)).divide(p2.y.subtract(p1.y)).multiply(new BigDecimal(-1));            m2 = (p3.x.subtract(p2.x)).divide(p3.y.subtract(p2.y)).multiply(new BigDecimal(-1));            mx1 = (p1.x.add(p2.x)).divide(new BigDecimal(2));            mx2 = (p2.x.add(p3.x)).divide(new BigDecimal(2));            my1 = (p1.y.add(p2.y)).divide(new BigDecimal(2));            my2 = (p2.y.add(p3.y)).divide(new BigDecimal(2));            xc = (m1.multiply(mx1).subtract(m2.multiply(mx2)).add(my2).subtract(my1)).divide(m1.subtract(m2));            yc = m1.multiply(xc.subtract(mx1)).add(my1);        }        BigDecimal dx = p2.x.subtract(xc);        BigDecimal dy = p2.y.subtract(yc);        BigDecimal rsqr = dx.pow(2).add(dy.pow(2));        dx = p.x.subtract(xc);        dy = p.y.subtract(yc);        BigDecimal drsqr = dx.pow(2).add(dy.pow(2));        if(drsqr.compareTo(rsqr) <= 0)            return true;        else            return false;    }    public static void main(String[] args) {        int t;        Scanner in = new Scanner(System.in);        t = in.nextInt();        while (t > 0) {            t--;            point[] a = new point[4];            for (int i = 0; i <= 3; ++i) {                a[i] = new point();                a[i].x = in.nextBigDecimal();                a[i].y = in.nextBigDecimal();            }            if(judge(a[3],a[0],a[1],a[2])){                System.out.println("Rejected");            }            else{                System.out.println("Accepted");            }        }    }}

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