3.1给出ax^2+bx+c的a.b.c系数，求根；
[java]view plaincopyprint?
importjava.util.Scanner;
publicclassC03t1{
publicstaticvoidmain(String[]args){
Scannerinput=newScanner(System.in);
System.out.println("请输入一元二次方程a,b,c系数的值\n请输入a:");
inta=input.nextInt();
System.out.println("请输入b:");
intb=input.nextInt();
System.out.println("请输入c:");
intc=input.nextInt();
intx=b*b-4*a*c;
doubley1,y2;
if(x<0)
System.out.println("方程无解");
elseif(x==0){
y1=(double)(-b)/(2*a);
System.out.println("有一个根为："+y1);
}
else{
y1=((double)(-b)+Math.pow(x,0.5))/2*a;
y2=((double)(-b)-Math.pow(x,0.5))/2*a;
System.out.println("有两个根为："+y1+"和"+y2);
}
}
}
3.8输入三个数，按大小显示
[java]view plaincopyprint?
importjavax.swing.JOptionPane;
publicclassC03t8{
publicstaticvoidmain(String[]args){
intnum1,num2,num3,temp;
Strings1=JOptionPane.showInputDialog("请输入第1个整数");
num1=Integer.parseInt(s1);
s1=JOptionPane.showInputDialog("请输入第2个整数");
num2=Integer.parseInt(s1);
s1=JOptionPane.showInputDialog("请输入第3个整数");
num3=Integer.parseInt(s1);
if(num1<num2){
temp=num2;
num2=num1;
num1=temp;
}
if(num1<num3){
temp=num3;
num3=num1;
num1=temp;
}
if(num3>num2){
temp=num3;
num3=num2;
num2=temp;
}
JOptionPane.showMessageDialog(null,"MAXNumberis"+num1+
";thesecondnumberis"+num2+";leastnumberis"+num3);
}
}
3.14猜硬币正反面扩展，1表示正面，0表示反面；可多次猜测，最终显示猜测的准确率。
[java]view plaincopyprint?
importjavax.swing.JOptionPane;
publicclassC03t14{
publicstaticvoidmain(String[]args){
intcount=0;//统计次数
intcorrectCount=0;//统计正确次数
Strings1="正面请选择是，反面请选择否";
Stringsz="本次投掷为正面,";
Stringsf="本次投掷为反面,";
Stringg1="恭喜你，猜对了";
Stringg2="很遗憾，猜错了";
Stringsx,gx;
while(JOptionPane.showConfirmDialog(null,"接着猜么？")==0){
intcoin=(int)(Math.random()*10)%2;
intanswer=JOptionPane.showConfirmDialog(null,s1);
if(coin==1)
sx=sz;
else
sx=sf;
if((coin==1&&answer==0)||(coin==0&&answer==1)){
gx=g1;
correctCount++;
}
else
gx=g2;
JOptionPane.showMessageDialog(null,sx+gx);
count++;
}
doublex=(double)correctCount/count*100;
JOptionPane.showMessageDialog(null,"你猜测准确率为"+x+"%.");
}
}
