算法提高 ADV-230 12-1三角形

问题描述

　　为二维空间中的点设计一个结构体，在此基础上为三角形设计一个结构体。分别设计独立的函数计算三角形的周长、面积、中心和重心。输入三个点，输出这三个点构成的三角形的周长、面积、外心和重心。结果保留小数点后2位数字。

样例输出

与上面的样例输入对应的输出。

例：



数据规模和约定

　  输入数据中每一个数的范围。
　　 例：doule型表示数据。

import java.util.Scanner;

public class Main {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
double [][] triangle = new double[3][2];

for (int i = 0; i < triangle.length; i++) {
triangle[i][0] = scanner.nextDouble();
triangle[i][1] = scanner.nextDouble();
}

double perimeter = getPerimeter(triangle);
double acreage = getAcreage(triangle);
double[] excenter =  getExcenter(triangle);
double[] barycenter = getBarycenter(triangle);
System.out.format("%.2f\n", perimeter );
System.out.format("%.2f\n", acreage);
System.out.format("%.2f", excenter[0]);
System.out.format(" %.2f\n", excenter[1]);
System.out.format("%.2f", barycenter[0]);
System.out.format(" %.2f\n", barycenter[1]);
}

/**
* 计算三角形的面积
* @param triangle
* @return
*/
private static double getAcreage(double[][] triangle) {
double [] edge = getABC( triangle );
double p = (edge[0] + edge[1] + edge[2]) / 2;
double acreage = Math.sqrt(
/*海伦公式 begin */
p * (p-edge[0]) * (p-edge[1]) * (p-edge[2])
/*海伦公式 end   */);

return acreage;
}

/**
* 计算三角形的重心（PS：三角形中三条边的中线交点）
* @param point
* @return
*/
public static double[] getBarycenter(double[][] point) {
double[] center = new double[2];
double x1 = point[0][0], y1 = point[0][1];
double x2 = point[1][0], y2 = point[1][1];
double x3 = point[2][0], y3 = point[2][1];
center[0] = (x1 + x2 + x3) / 3;  //重心的横坐标
center[1] = (y1 + y2 + y3) / 3;  //重心的纵坐标
return center;
}

/**
* 计算三角形的周长
* @param triangle
* @return
*/
priv
a577
ate static double getPerimeter(double[][] triangle) {
double result = 0;
double [] edge = getABC( triangle );
for (int i = 0; i < edge.length; i++) {
result += edge[i];
}
return result;
}

/**
* 计算三角形三条边的边长
* @param triangle
* @return
*/
public static double[] getABC(double[][] triangle){
double [] edge = new double[3];
double x1 = triangle[0][0];
double y1 = triangle[0][1];

double x2 = triangle[1][0];
double y2 = triangle[1][1];

double x3 = triangle[2][0];
double y3 = triangle[2][1];

edge[0] = getSqrt(x1,x2,y1,y2);
edge[1] = getSqrt(x1, x3, y1, y3);
edge[2] = getSqrt(x2, x3, y2, y3);

return edge;
}

//计算三角形的外心（PS：三角形外接圆的圆心，外心到三个顶点距离相等）
public static double[] getExcenter(double[][] triangle) {
double[] center = new double[2];
double x1 = triangle[0][0], y1 = triangle[0][1];
double x2 = triangle[1][0], y2 = triangle[1][1];
double x3 = triangle[2][0], y3 = triangle[2][1];
double a , b , c , d ;
a = (x1*x1 + y1*y1 - x2*x2 - y2*y2) * (x1 - x3) / 2;
b = (x1*x1 + y1*y1 - x3*x3 - y3* y3) * (x1 - x2) / 2;
c = (y1 - y2) * (x1 - x3);
d = (y1 - y3) * (x1 - x2);
center[1] = (a - b) / (c - d);  //外心的纵坐标
double e, f;
if(x1 != x2) {   //防止出现两点的横坐标相等的情况
e = (x1*x1 + y1*y1 - x2*x2 - y2*y2) / (2 * (x1 - x2));
f = (y1 - y2) / (x1 - x2);
center[0] = e - f * center[1];  //外心的横坐标
} else if(x1 != x3) {
e = (x1*x1 + y1*y1 - x3*x3 - y3*y3) / (2 * (x1 - x3));
f = (y1 - y3) / (x1 - x3);
center[0] = e - f * center[1];
} else if(x2 != x3) {
e = (x2*x2 + y2*y2 - x3*x3 - y3*y3) / (2 * (x2 - x3));
f = (y2 - y3) / (x2 - x3);
center[0] = e - f * center[1];
}
return center;
}

/**
* 求单条边的边长
* @param x1
* @param x2
* @param y1
* @param y2
* @return
*/
private static double getSqrt(double x1, double x2, double y1, double y2) {
double squareNum =  (x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2);
return Math.sqrt(squareNum);
}
}