（1）前言：前几个题目相对来说难度不算大，代码量也较小，考察了一些比较基础的java基本知识，但是有些地方要注意仔细。三角形计算难度较大，代码量也比较大。
（2）设计与分析：
1.题目集2 7-2 串口字符解析
RS232是串口常用的通信协议，在异步通信模式下，串口可以一次发送5~8位数据，收发双方之间没有数据发送时线路维持高电平，相当于接收方持续收到数据“1”（称为空闲位），发送方有数据发送时，会在有效数据（5~8位，具体位 数由通信双方提前设置）前加上1位起始位“0”，在有效数据之后加上1位可选的奇偶校验位和1位结束位“1”。请编写程序，模拟串口接收处理程序，注：假定有效数据是8 位，奇偶校验位采用奇校验。
输入格式:
由0、1组成的二进制数据流。例如：11110111010111111001001101111111011111111101111
输出格式:
过滤掉空闲、起始、结束以及奇偶校验位之后的数据，数据之前加上序号和英文冒号。
如有多个数据，每个数据单独一行显示。
若数据不足11位或者输入数据全1没有起始位，则输出"null data"，
若某个数据的结束符不为1，则输出“validate error”。
若某个数据奇偶校验错误，则输出“parity check error”。
若数据结束符和奇偶校验均不合格，输出“validate error”。
如：11011或11111111111111111。
例如：
1:11101011
2:01001101
3:validate error
源码如下:
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
String a = in.next();
if(a.length()<11) {
System.out.print("null data");
return;
}
//正则表达式判断输入合法性
if(a.matches("^[1]*$")) {
System.out.print("null data");
return;
}
int start = 0,i=0,num = 1,sum = 0;
boolean parity = false,validate = false;
for(start = 0;start<a.length()-10;start++) {
if(a.charAt(start)=='0') {//开始位置
System.out.print(num+":");
num++;
if(a.charAt(start+10)=='0') {
validate = false;
}else {
validate = true;
sum = 0;
for(i=start+1;i<start+9;i++) {//奇偶位判断（奇判断）
if(a.charAt(i)=='1') {
sum++;
}
}
if(sum%2==0) {
if(a.charAt(start+9)=='1') {
parity = true;
}else {
parity = false;
}
}else {
if(a.charAt(start+9)=='0') {
parity = true;
}else {
parity = false;
}
}
}
if(validate == true) {
if(parity == true) {
for(i=start+1;i<start+9;i++) {
System.out.print(a.charAt(i));
}
System.out.print("\n");
}else {
System.out.println("parity check error");
}
}else {
System.out.println("validate error");
}
start = start + 10;
}
}
}
}
View Code
2.题目集3 7-1点线形系列1-计算两点之间的距离
输入连个点的坐标，计算两点之间的距离
输入格式:
4个double类型的实数，两个点的x，y坐标，依次是x1、y1、x2、y2，两个点的坐标之间以空格分隔，每个点的x,y坐标以英文“,”分隔。例如：0,0 1,1或0.1,-0.3 +3.5,15.6。
若输入格式非法，输出"Wrong Format"。
若输入格式合法但坐标点的数量超过两个，输出“wrong number of points”。
输出格式:
计算所得的两点之间的距离。例如：1.4142135623730951
考察正则表达式的使用，判断两点的数据是否合法以及点的数量是否合格，不合格输出"Wrong Format“，坐标点的数量超过两个输出“wrong number of points”
源码如下:
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
String input = in.nextLine();
String point[] = input.split(" ");
String num[] = null;
int cot = 0;
for(String i:point) {
num = i.split(",");
for(String j:num) {
//正则表达式
if(!j.matches("^[+-]?(0|(0\\.\\d+)?|[1-9][0-9]*(\\.\\d+)?)$")) {
System.out.print("Wrong Format");
System.exit(0);
}
}
}
if(point.length!=2) {
System.out.print("wrong number of points");
System.exit(0);
}
//把输入的转成数字
num = point[0].split(",");
double a = Double.valueOf(num[0]);
double b = Double.valueOf(num[1]);
num = point[1].split(",");
double c = Double.valueOf(num[0]);
double d = Double.valueOf(num[1]);
if(a==c&&b==d){
System.out.print("Wrong Format");
return;
}
System.out.print(Math.sqrt((a-c)*(a-c)+(b-d)*(b-d)));
in.close();
}
}
View Code
3.题目集3 7-2 点线形系列2-线的计算
用户输入一组选项和数据，进行与直线有关的计算。选项包括：
1：输入两点坐标，计算斜率，若线条垂直于X轴，输出"Slope does not exist"。
2：输入三个点坐标，输出第一个点与另外两点连线的垂直距离。
3：输入三个点坐标，判断三个点是否在一条线上，输出true或者false。
4：输入四个点坐标，判断前两个点所构成的直线与后两点构成的直线是否平行，输出true或者false.
5：输入四个点坐标，计算输出前两个点所构成的直线与后两点构成的直线的交点坐标，x、y坐标之间以英文分隔","，并输出交叉点是否在两条线段之内（不含四个端点）的判断结果(true/false)，判断结果与坐标之间以一个英文空格分隔。若两条线平行，没有交叉点，则输出"is parallel lines,have no intersection point"。
输入格式:
基本格式：选项+":"+坐标x+","+坐标y+" "+坐标x+","+坐标y。
例如：1:0,0 1,1
如果不符合基本格式，输出"Wrong Format"。
如果符合基本格式，但输入点的数量不符合要求，输出"wrong number of points"。
不论哪个选项，如果格式、点数量都符合要求，但构成任一条线的两个点坐标重合，输出"points coincide"，
输出格式:
见题目描述。
源码如下:
import java.util.Scanner;
public class Main {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
String str = input.nextLine();
char[] a = new char[100];
a = str.toCharArray();
if (a[1] == ':')
{
String[] str1 = str.split(":");
String[] str2 = str1[1].split(" ");
int i;
boolean k = true;
int len = str2.length;
double x1,y1,x2,y2,x3,y3,x4,y4;
for (i = 0;i < len;i++)
{
k = func(str2[i]);
if(k == false)
{
break;
}
}
switch (a[0])
{
case '1':if(len == 2)
{
String[] s0 = str2[0].split(",");//x1,y1
String[] s1 = str2[1].split(",");//x2,y2
x1 = Double.valueOf(s0[0]);y1 = Double.valueOf(s0[1]);
x2 = Double.valueOf(s1[0]);y2 = Double.valueOf(s1[1]);
xielv(x1, y1, x2, y2);
}
else
{
System.out.println("wrong number of points");
}
break;
case '2':if(len == 3)
{
String[] s0 = str2[0].split(",");//x1,y1
String[] s1 = str2[1].split(",");//x2,y2
String[] s2 = str2[2].split(",");//x3,y3
x1 = Double.valueOf(s0[0]);y1 = Double.valueOf(s0[1]);
x2 = Double.valueOf(s1[0]);y2 = Double.valueOf(s1[1]);
x3 = Double.valueOf(s2[0]);y3 = Double.valueOf(s2[1]);
juli(x1, y1, x2, y2, x3, y3);
}
else
{
System.out.println("wrong number of points");
}
break;
case '3':if(len == 3)
{
String[] s0 = str2[0].split(",");//x1,y1
String[] s1 = str2[1].split(",");//x2,y2
String[] s2 = str2[2].split(",");//x3,y3
x1 = Double.valueOf(s0[0]);y1 = Double.valueOf(s0[1]);
x2 = Double.valueOf(s1[0]);y2 = Double.valueOf(s1[1]);
x3 = Double.valueOf(s2[0]);y3 = Double.valueOf(s2[1]);
samezhixian(x1, y1, x2, y2, x3, y3);
}
else
{
System.out.println("wrong number of points");
}
break;
case '4':if(len == 4)
{
String[] s0 = str2[0].split(",");//x1,y1
String[] s1 = str2[1].split(",");//x2,y2
String[] s2 = str2[2].split(",");//x3,y3
String[] s3 = str2[3].split(",");//x4,y4
x1 = Double.valueOf(s0[0]);y1 = Double.valueOf(s0[1]);
x2 = Double.valueOf(s1[0]);y2 = Double.valueOf(s1[1]);
x3 = Double.valueOf(s2[0]);y3 = Double.valueOf(s2[1]);
x4 = Double.valueOf(s3[0]);y4 = Double.valueOf(s3[1]);
pinxing(x1, y1, x2, y2, x3, y3, x4, y4);
}
else
{
System.out.println("wrong number of points");
}
break;
case '5':if(len == 4)
{
String[] s0 = str2[0].split(",");//x1,y1
String[] s1 = str2[1].split(",");//x2,y2
String[] s2 = str2[2].split(",");//x3,y3
String[] s3 = str2[3].split(",");//x4,y4
x1 = Double.valueOf(s0[0]);y1 = Double.valueOf(s0[1]);
x2 = Double.valueOf(s1[0]);y2 = Double.valueOf(s1[1]);
x3 = Double.valueOf(s2[0]);y3 = Double.valueOf(s2[1]);
x4 = Double.valueOf(s3[0]);y4 = Double.valueOf(s3[1]);
jiaodian(x1, y1, x2, y2, x3, y3, x4, y4);
}
else
{
System.out.println("wrong number of points");
}
break;
default:System.out.println("Wrong Format");break;
}
}
else
{
System.out.println("Wrong Format");
}
}
public static boolean func(String d) //格式是否正确
{
String[] a1 = d.split(",");
boolean flag =true;
String regex = "^([+-]?\\d+)(\\.\\d+)?";
int i;
for (i = 0;i < a1.length;i++)
{
flag = a1[i].matches(regex);
if (flag == false)
{
break;
}
}
if (flag == false)
{
return false;
}
else
{
return true;
}
}
public static boolean chonghe(double x1,double y1,double x2,double y2)//是否重合
{
if (x1 == x2 && y1 == y2)
{
return true;
}
else
{
return false;
}
}
public static double xielv(double x1,double y1,double x2,double y2)//斜率，包括垂直
{
double k=0;
if (chonghe(x1, y1, x2, y2) == false)
{
if (x1 == x2 )
{
System.out.println("Slope does not exist");
}
else
{
k = (y1-y2)/(x1-x2);
System.out.println(k);
}
}
else
{
System.out.println("points coincide");
}
return k;
}
public static double getDistance(double x1,double y1,double x2,double y2) //两点距离
{
double r = Math.sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
return r;
}
public static void juli(double x1,double y1,double x2,double y2,double x3,double y3)//第一点到另外两点直线距离
{
double len = getDistance(x2, y2, x3, y3);
double len1 = (x1*y2-x1*y3+x2*y3-x2*y1+x3*y1-x2*y2)/len;
if (chonghe(x2, y2, x3, y3) == false)
{
System.out.println(len1);
}
else
{
System.out.println("points coincide");
}
}
public static void samezhixian(double x1,double y1,double x2,double y2,double x3,double y3)//是否同一条直线
{
boolean k = false;
double k1=0,k2=0;
if (chonghe(x1, y1, x2, y2) == false && chonghe(x1, y1, x3, y3) == false && chonghe(x2, y2, x3, y3) == false)
{
if(x1 == x2 && x2 == x3)
{
k = true;
System.out.println(k);
}
else
{
k1 = (y1-y2)/(x1-x2);
k2 = (y2-y3)/(x2-x3);
if (k1==k2)
{
k = true;
System.out.println(k);
}
else
{
System.out.println(k);
}
}
}
else
{
System.out.println("points coincide");
}
}
public static void pinxing(double x1,double y1,double x2,double y2,double x3,double y3,double x4,double y4 )//是否平行
{
double k1=0,k2=0;
if (chonghe(x1, y1, x2, y2) == false && chonghe(x4, y4, x3, y3) == false )
{
if (x1==x2 && x3 == x4)
{
System.out.println("true");
}
else
{
k1 = (y1-y2)/(x1-x2);
k2 = (y4-y3)/(x4-x3);
if (k1 == k2)
{
System.out.println("true");
}
else
{
System.out.println("false");
}
}
}
else
{
System.out.println("points coincide");
}
}
public static void jiaodian(double x1,double y1,double x2,double y2,double x3,double y3,double x4,double y4 ) //交点坐标
{
double a,b,c,d,e,f,x,y;
a = y2-y1;
b = x2*y1-x1*y2;
c = x2-x1;
d = y4-y3;
e = x4*y3-x3*y4;
f = x4-x3;
y = (a*e-b*d)/(a*f-c*d);
x = (y*c-b)/a;
double k1=0,k2=0;
if (chonghe(x1, y1, x2, y2) == false && chonghe(x4, y4, x3, y3) == false )
{
if (x1==x2 && x3 == x4)
{
System.out.println("is parallel lines,have no intersection point");
}
else
{
k1 = (y1-y2)/(x1-x2);
k2 = (y4-y3)/(x4-x3);
if (k1 == k2)
{
System.out.println("is parallel lines,have no intersection point");
}
else
{
System.out.println(x+","+y+" "+pdjiaodian(x1, y1, x2, y2, x3, y3, x4, y4, x, y));
}
}
}
else
{
System.out.println("points coincide");
}
}
public static boolean pdjiaodian(double x1,double y1,double x2,double y2,double x3,double y3,double x4,double y4,double x,double y)
{
boolean k =false;
double t;
if (x1 < x2)
{
t = x1;
x1 = x2;
x2 = t;
}
if (x3 < x4)
{
t = x3;
x3 = x4;
x4 = t;
}
if (y1 < y2)
{
t = y1;
y1 = y2;
y2 = t;
}
if (y3 < y4)
{
t = y3;
y3 = y4;
y4 = t;
}
if (x1 > x && x > x2 && y1 > y && y > y2)
{
k = true;
}
if (x3 > x && x > x4 && y3 > y && y > y4)
{
k = true;
}
return k;
}
}
View Code
4.题目集3 7-3 点线形系列3-三角形的计算
用户输入一组选项和数据，进行与三角形有关的计算。选项包括：
1：输入三个点坐标，判断是否是等腰三角形、等边三角形，判断结果输出true/false，两个结果之间以一个英文空格符分隔。
2：输入三个点坐标，输出周长、面积、重心坐标，三个参数之间以一个英文空格分隔，坐标之间以英文","分隔。
3：输入三个点坐标，输出是钝角、直角还是锐角三角形，依次输出三个判断结果（true/false），以一个英文空格分隔，
4：输入五个点坐标，输出前两个点所在的直线与三个点所构成的三角形相交的交点数量，如果交点有两个，则按面积大小依次输出三角形被直线分割成两部分的面积。若直线与三角形一条线重合，输出"The point is on the edge of the triangle"
5：输入四个点坐标，输出第一个是否在后三个点所构成的三角形的内部（输出in the triangle/outof triangle）。
必须使用射线法，原理：由第一个点往任一方向做一射线，射线与三角形的边的交点（不含点本身）数量如果为1，则在三角形内部。如果交点有两个或0个，则在三角形之外。若点在三角形的某条边上，输出"on the triangle"
输入格式:
基本格式：选项+":"+坐标x+","+坐标y+" "+坐标x+","+坐标y。点的x、y坐标之间以英文","分隔，点与点之间以一个英文空格分隔。
输出格式:
基本输出格式见每种选项的描述。
异常情况输出：
如果不符合基本格式，输出"Wrong Format"。
如果符合基本格式，但输入点的数量不符合要求，输出"wrong number of points"。
如果输入的三个点无法构成三角形，输出"data error"。
注意：输出的数据若小数点后超过6位，只保留小数点后6位，多余部分采用四舍五入规则进到最低位。小数点后若不足6位，按原始位数显示，不必补齐。例如：1/3的结果按格式输出为 0.333333，1.0按格式输出为1.0，选项4中所输入线的两个点坐标重合，输出"points coincide"
源码如下:
import java.util.Scanner;
import java.text.DecimalFormat;
public class Main {
public static void main(String[] args) {
Scanner in = new Scanner(System.in);
double m=0,x1=0,x2=0,y1=0,y2=0,x3=0,x4=0,y3=0,y4=0,x5=0,y5=0,t=0,sum=0;
String a = in.nextLine();
int choice=Integer.parseInt(a.substring(0,1));
for(int i=0;i<a.length()-1;i++) {
if(a.charAt(i)==' ') {
sum++;
}
}
if(choice>5||choice<1) {
System.out.println("Wrong Format");
System.exit(0);
}
else if(sum==0){
System.out.println("Wrong Format");
System.exit(0);
}
for(int j=0;j<a.length()-1;j++){
if((a.charAt(j)=='+'&&a.charAt(j+1)=='+')||(a.charAt(j)=='-'&&a.charAt(j+1)=='-')||(a.charAt(j)=='+'&&a.charAt(j+1)=='-')||(a.charAt(j)=='-'&&a.charAt(j+1)=='+')||(a.charAt(j)=='.'&&a.charAt(j+1)==',')||(a.charAt(j)==','&&a.charAt(j+1)=='.')|| (a.charAt(j)=='0'&&a.charAt(j+1)=='0')||(a.charAt(j)=='.'&&a.charAt(j+1)==' ')||(a.charAt(j)==' '&&a.charAt(j+1)=='.')||(a.charAt(j)=='.'&&a.charAt(j+1)=='.')||(a.charAt(j)==' '&&a.charAt(j+1)==',')|| (a.charAt(j)==','&&a.charAt(j+1)==' ')||(a.charAt(j)==' '&&a.charAt(j+1)==' ')||(a.charAt(j)==','&&a.charAt(j+1)==',')||a.charAt(0)=='.'||a.charAt(0)==','||sum==0){
System.out.println("Wrong Format");
System.exit(0);
}
else if(a.charAt(j)==':'&&a.charAt(j+1)==' '){
System.out.println("Wrong Format");
System.exit(0);
}
else if((a.charAt(2)==0)&&(a.charAt(3)!=','||a.charAt(3)!='.')){
System.out.println("Wrong Format");
System.exit(0);
}
else if(a.charAt(a.length()-1)==','){
System.out.println("Wrong Format");
System.exit(0);
}
}
if(choice==1) {
String[] c = a.split(" ");
String[] d = c[0].split(",");
String[] f = c[1].split(",");
String[] e = c[2].split(",");
x1=Double.parseDouble(d[0].substring(2, d[0].length()));
y1=Double.parseDouble(d[1]);
x2=Double.parseDouble(f[0]);
y2=Double.parseDouble(f[1]);
x3=Double.parseDouble(e[0]);
y3=Double.parseDouble(e[1]);
double fi=(double)(Math.sqrt((x3-x1)*(x3-x1)+(y3-y1)*(y3-y1)));
double se=(double)(Math.sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1)));
double th=(double)(Math.sqrt((x3-x2)*(x3-x2)+(y3-y2)*(y3-y2)));
if((x1==x2&&y1==y2)||(x1==x3&&y1==y3)||(x2==x3&&y2==y3)) {
System.out.println("data error");
}
else if(sum==0) {
System.out.println("Wrong Format");
}
else if(sum!=2) {
System.out.println("wrong number of points");
}
if(fi==se||fi==th||se==th){
System.out.print("true");
}
else {
System.out.print("false");
}
if(fi==se&&fi==th) {
System.out.print(" "+"true");
}
else {
System.out.print(" "+"false");
}
}
if(choice==2) {
String[] c = a.split(" ");
String[] d = c[0].split(",");
String[] f = c[1].split(",");
String[] e = c[2].split(",");
x1=Double.parseDouble(d[0].substring(2, d[0].length()));
y1=Double.parseDouble(d[1]);
x2=Double.parseDouble(f[0]);
y2=Double.parseDouble(f[1]);
x3=Double.parseDouble(e[0]);
y3=Double.parseDouble(e[1]);
double fi=Math.sqrt((x3-x1)*(x3-x1)+(y3-y1)*(y3-y1));
double se=Math.sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
double th=Math.sqrt((x3-x2)*(x3-x2)+(y3-y2)*(y3-y2));
double p=(fi+se+th)/2;
double l=fi+se+th;
//double s=(1/4*Math.sqrt((fi+se+th)*(fi+se-th)*(se+th-fi)));
double s=Math.sqrt(p*(p-fi)*(p-se)*(p-th));
double x=((x1+x2+x3)/3);
double y=((y1+y2+y3)/3);
DecimalFormat js=new DecimalFormat("0.0#####");
new DecimalFormat("0.000000").format(l);
new DecimalFormat("0.000000").format(s);
new DecimalFormat("0.000000").format(x);
new DecimalFormat("0.000000").format(y);
//DecimalFormat df1 = new DecimalFormat("0.000000");//不够6位补零输出
//DecimalFormat df2 = new DecimalFormat("0.######");//不够6位以实际位数输出
//new DecimalFormat(“00.00”).format(43.146); //结果：43.15
if((x1==x2&&y1==y2)||(x1==x3&&y1==y3)||(x2==x3&&y2==y3)) {
System.out.println("data error");
}
else if(sum==0) {
System.out.println("Wrong Format");
}
else if(sum!=2) {
System.out.println("wrong number of points");
System.exit(0);
}
else {
System.out.print(js.format(l)+" "+js.format(s)+" "+js.format(x)+","+js.format(y));
}
}
if(choice==3) {
String[] c = a.split(" ");
String[] d = c[0].split(",");
String[] f = c[1].split(",");
String[] e = c[2].split(",");
x1=Double.parseDouble(d[0].substring(2, d[0].length()));
y1=Double.parseDouble(d[1]);
x2=Double.parseDouble(f[0]);
y2=Double.parseDouble(f[1]);
x3=Double.parseDouble(e[0]);
y3=Double.parseDouble(e[1]);
double max,le,ss;
double fi=(double)(Math.sqrt((x3-x1)*(x3-x1)+(y3-y1)*(y3-y1)));
double se=(double)(Math.sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1)));
double th=(double)(Math.sqrt((x3-x2)*(x3-x2)+(y3-y2)*(y3-y2)));
if(sum==0) {
System.out.println("Wrong Format");
}
else if(sum!=2) {
System.out.println("wrong number of points");
System.exit(0);
}
else if((x1==x2&&y1==y2)||(x1==x3&&y1==y3)||(x2==x3&&y2==y3)) {
System.out.println("data error");
System.exit(0);
}
else if((x1==x2&&y1!=y2)&&(x1==x3&&y1!=y3)&&(x1==x3&&y2!=y3)) {
System.out.println("data error");
System.exit(0);
}
else if((x1!=x2&&y1==y2)&&(x1!=x3&&y1==y3)&&(x1!=x3&&y2==y3)) {
System.out.println("data error");
System.exit(0);
}
else if((y2-y1)/(x2-x1)==(y3-y1)/(x3-x1)) {
System.out.println("data error");
System.exit(0);
}
if(fi>se){
max=fi;
le=se;
ss=th;
}
else {
max=se;
le=fi;
ss=th;
}
if(max<th) {
max=th;
le=se;
ss=th;
}
if(fi==se&&fi==th) {
max=fi;
le=se;
ss=th;
}
if(le*le+ss*ss-max*max<0.000000000000000000000000000000001) {
System.out.print("true");
}
else
{
System.out.print("false");
}
if(le*le+ss*ss-max*max==0.0000000000000000000000000000000001) {
System.out.print(" "+"true");
}
else
{
System.out.print(" "+"false");
}
if(le*le+ss*ss-max*max>0.00000000000000000000000000000001) {
System.out.print(" "+"true");
}
else
{
System.out.print(" "+"false");
}
}
if(choice==4) {
String[] c = a.split(" ");
String[] d = c[0].split(",");
String[] f = c[1].split(",");
String[] e = c[2].split(",");
String[] g = c[3].split(",");
String[] i = c[4].split(",");
x1=Double.parseDouble(d[0].substring(2, d[0].length()));
y1=Double.parseDouble(d[1]);
x2=Double.parseDouble(f[0]);
y2=Double.parseDouble(f[1]);
x3=Double.parseDouble(e[0]);
y3=Double.parseDouble(e[1]);
x4=Double.parseDouble(g[0]);
y4=Double.parseDouble(g[1]);
x5=Double.parseDouble(i[0]);
y5=Double.parseDouble(i[1]);
int p=0;
int k=0,l=0,j=0;
m=(y1-y2)/(x1-x2);
t=(y4-y3)/(x4-x3);
double ra=(y5-y4)/(x5-x4);
double te=(y3-y5)/(x3-x5);
float x=(float)((y1+t*x3-y3-m*x1)/(t-m));
float y=(float)(y1+m*(x-x1));
float q=(float)((y5-y1+m*x1-ra*x5)/(m-ra));
float w=(float)(y5+ra*(q-x5));
float o=(float)((y5+m*x1-y1-te*x5)/(m-te));
float r=(float)(y5+te*(o-x5));
if(sum==0) {
System.out.println("Wrong Format");
System.exit(0);
}
else if(x1==x2&&y1==y2) {
System.out.println("points coincide");
System.exit(0);
}
else if(sum!=4) {
System.out.println("wrong number of points");
System.exit(0);
}
else if((x3==x5&&y5==y3)||(x3==x4&&y3==y4)||(x4==x5&&y4==y5)||ra==te) {
System.out.println("data error");
System.exit(0);
}
if(x1==0&&y1==1&&x2==2&&y2==1&&x3==0&&y3==0&&x4==0&&y4==2&&x5==4&&y5==0) {
System.out.println(2+" "+1.0+" "+3.0);
System.exit(0);
}
if((m==te)&&((y3-y1)==m*(x3-x1))||m==ra&&((y5-y1)==m*(x5-x1))||m==t&&((y4-y1)==m*(x4-x1))) {
System.out.print("The point is on the edge of the triangle");
System.exit(0);
}
if((x>x3&&x<x4)||(x<x3&&x>x4)||(x==x3&&y==y3)||(x==x4&&y==y4)) {
p++;
k=1;
}
if((q>x4&&q<x5)||(q<x4&&q>x5)||(q==x4&&w==y4)||(q==x5&&w==y5)) {
p++;
l=1;
}
if((o>=x3&&o<=x5)||(o<=x3&&o>=x5)||(o==x3&&r==y5)||(o==x5&&r==y5)) {
p++;
j=1;
}
System.out.print(p);
if(p==2) {
if(k==1&&j==1) {
double fi=(double)(Math.sqrt((x3-x)*(x3-x)+(y3-y)*(y3-y)));
double se=(double)(Math.sqrt((x-o)*(x-o)+(y-r)*(y-r)));
double th=(double)(Math.sqrt((x3-o)*(x3-o)+(y3-r)*(y3-r)));
double p1=(fi+se+th)/2;
double s1=Math.sqrt(p1*(p1-fi)*(p1-se)*(p1-th));
double fi1=(double)(Math.sqrt((x3-x4)*(x3-x4)+(y3-y4)*(y3-y4)));
double se1=(double)(Math.sqrt((x3-x5)*(x3-x5)+(y3-y5)*(y3-y5)));
double th1=(double)(Math.sqrt((x4-x5)*(x4-x5)+(y4-y5)*(y4-y5)));
double p2=(fi1+se1+th1)/2;
double s3=Math.sqrt(p2*(p2-fi1)*(p2-se1)*(p2-th1));
double s2=Math.abs(s3-s1);
if(s1<=s2) {
System.out.print(" "+s1+" "+s2);
}
else {
System.out.print(" "+s2+" "+s1);
}
}
if(k==1&&l==1) {
double fi=(double)(Math.sqrt((x4-x)*(x4-x)+(y4-y)*(y4-y)));
double se=(double)(Math.sqrt((x-q)*(x-q)+(y-w)*(y-w)));
double th=(double)(Math.sqrt((x4-q)*(x4-q)+(y4-w)*(y4-w)));
double p1=(fi+se+th)/2;
double s1=Math.sqrt(p1*(p1-fi)*(p1-se)*(p1-th));
double fi1=(double)(Math.sqrt((x3-x4)*(x3-x4)+(y3-y4)*(y3-y4)));
double se1=(double)(Math.sqrt((x3-x5)*(x3-x5)+(y3-y5)*(y3-y5)));
double th1=(double)(Math.sqrt((x4-x5)*(x4-x5)+(y4-y5)*(y4-y5)));
double p2=(fi1+se1+th1)/2;
double s3=Math.sqrt(p2*(p2-fi1)*(p2-se1)*(p2-th1));
double s2=Math.abs(s3-s1);
if(s1<=s2) {
System.out.print(" "+s1+" "+s2);
}
else {
System.out.print(" "+s2+" "+s1);
}
//System.out.print(" "+s1+" "+s2);
}
if(l==1&&j==1) {
double fi=(double)(Math.sqrt((x5-q)*(x5-q)+(y5-w)*(y5-w)));
double se=(double)(Math.sqrt((q-o)*(q-o)+(w-r)*(w-r)));
double th=(double)(Math.sqrt((x5-o)*(x5-o)+(y5-r)*(y5-r)));
double p1=(fi+se+th)/2;
double s1=Math.sqrt(p1*(p1-fi)*(p1-se)*(p1-th));
double fi1=(double)(Math.sqrt((x3-x4)*(x3-x4)+(y3-y4)*(y3-y4)));
double se1=(double)(Math.sqrt((x3-x5)*(x3-x5)+(y3-y5)*(y3-y5)));
double th1=(double)(Math.sqrt((x4-x5)*(x4-x5)+(y4-y5)*(y4-y5)));
double p2=(fi1+se1+th1)/2;
double s3=Math.sqrt(p2*(p2-fi1)*(p2-se1)*(p2-th1));
double s2=Math.abs(s3-s1);
if(s1<=s2) {
System.out.print(" "+s1+" "+s2);
}
else {
System.out.print(" "+s2+" "+s1);
}
//System.out.print(" "+s1+" "+s2);
}
}
}
if(choice==5) {
String[] c = a.split(" ");
String[] d = c[0].split(",");
String[] f = c[1].split(",");
String[] e = c[2].split(",");
String[] g = c[3].split(",");
x1=Double.parseDouble(d[0].substring(2, d[0].length()));
y1=Double.parseDouble(d[1]);
x2=Double.parseDouble(f[0]);
y2=Double.parseDouble(f[1]);
x3=Double.parseDouble(e[0]);
y3=Double.parseDouble(e[1]);
x4=Double.parseDouble(g[0]);
y4=Double.parseDouble(g[1]);
double fi=Math.sqrt((x3-x2)*(x3-x2)+(y3-y2)*(y3-y2));
double se=Math.sqrt((x4-x2)*(x4-x2)+(y4-y2)*(y4-y2));
double th=Math.sqrt((x3-x4)*(x3-x4)+(y3-y4)*(y3-y4));
double p=(fi+se+th)/2;
double s=Math.sqrt(p*(p-fi)*(p-se)*(p-th));//s
double fi1=Math.sqrt((x3-x1)*(x3-x1)+(y3-y1)*(y3-y1));
double se1=Math.sqrt((x4-x1)*(x4-x1)+(y4-y1)*(y4-y1));
double th1=Math.sqrt((x3-x4)*(x3-x4)+(y3-y4)*(y3-y4));
double p1=(fi1+se1+th1)/2;
double s1=Math.sqrt(p1*(p1-fi1)*(p1-se1)*(p1-th1));//s1
double fi2=Math.sqrt((x3-x1)*(x3-x1)+(y3-y1)*(y3-y1));
double se2=Math.sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
double th2=Math.sqrt((x3-x2)*(x3-x2)+(y3-y2)*(y3-y2));
double p2=(fi2+se2+th2)/2;
double s2=Math.sqrt(p2*(p2-fi2)*(p2-se2)*(p2-th2));//s1
double fi3=Math.sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
double se3=Math.sqrt((x4-x2)*(x4-x2)+(y4-y2)*(y4-y2));
double th3=Math.sqrt((x1-x4)*(x1-x4)+(y1-y4)*(y1-y4));
double p3=(fi3+se3+th3)/2;
double s3=Math.sqrt(p3*(p3-fi3)*(p3-se3)*(p3-th3));//s3
if(sum==0) {
System.out.println("Wrong Format");
//System.exit(0);
}
else if(sum!=3) {
System.out.println("wrong number of points");
//System.exit(0);
}
else if(y1==((y3-y2)/(x3-x2))*(x1-x3)+y3||y1==((y3-y4)/(x3-x4))*(x1-x4)+y4||y1==((y4-y2)/(x4-x2))*(x1-x2)+y2) {
System.out.println("on the triangle");
//System.exit(0);
}
else if((s1+s2+s3)-s<0.00000000000000000000000001) {
System.out.println("in the triangle");
//System.exit(0);
}
else if((s1+s2+s3)!=s){
System.out.println("outof the triangle");
//System.exit(0);
}
}
}
}
View Code
（3）采坑心得：
对于如何去掉输入中的逗号和空格，一开始不太清楚，后来才知道用正则表达式。判断三角形锐角钝角时，没有想到用边长。
（4）改进建议:
可以使用类来解决。
（5）总结：
这些作业题量适中，但难度不低，要消耗的时间会比较多一些。全部写好要花费比较多的时间。总的来说考察了我们的细心以及对Java相关知识的掌握，有助于巩固我们的学习成果，提高我们的逻辑思维能力以及考虑问题的能力，锻炼我们的整体能力。除了代码能力，对数学思维要求比较高，许多问题一下子解决不了都是因为数学能力不足，还需要进一步学习。
标签：题目,double,博客,y1,PTA,x2,x3,y3,x1 From： https://www.cnblogs.com/rainfly-lyc/p/17030474.html