二分绝对值,推断是否存在对应的矩阵
import java.util.*; public class Main { double a,b,c,d; double[][] range = new double[4][2]; double getMin(double L,double R,double l,double r) { return Math.min(L*l,Math.min(L*r,Math.min(R*l,R*r))); } double getMax(double L,double R,double l,double r) { return Math.max(L*l,Math.max(L*r,Math.max(R*l,R*r))); } boolean check(double e) { range[0][0]=a-e; range[0][1]=a+e; // x range[1][0]=b-e; range[1][1]=b+e; // y range[2][0]=c-e; range[2][1]=c+e; // z range[3][0]=d-e; range[3][1]=d+e; // w double A=getMin(range[0][0],range[0][1],range[3][0],range[3][1]); double B=getMax(range[0][0],range[0][1],range[3][0],range[3][1]); double C=getMin(range[1][0],range[1][1],range[2][0],range[2][1]); double D=getMax(range[1][0],range[1][1],range[2][0],range[2][1]); if((A>=C&&A<=D)||(B>=C&&B<=D)||(C>=A&&C<=B)||(D>=A&&D<=B)) return true; return false; } double Search() { double low=0.00000,high=100000000000.; int T_T=170; while(T_T-->0) { double mid=(low+high)/2.; if(check(mid)==true) high=mid; else low=mid; } return high; } Main() { Scanner in = new Scanner(System.in); a=in.nextDouble(); b=in.nextDouble(); c=in.nextDouble(); d=in.nextDouble(); System.out.printf("%.12f ",Search()); } public static void main(String[] args) { new Main(); } }