風情

// hw7_1,
public class hw7_1
{
public static void main(String args[])
{
proverb();
}

public static void proverb()
{
System.out.println("Two heads are better than one.");
}
}

/* output----------------------
Two heads are better than one.
-----------------------------*/
// hw7_2,
public class hw7_2
{
public static void main(String args[])
{
proverb(3);
}

public static void proverb(int k)
{
for(int i=1;i System.out.println("Live and learn.");
}
}

/* output---------
Live and learn.
Live and learn.
Live and learn.
----------------*/
// hw7_3,
public class hw7_3
{
public static void main(String args[])
{
System.out.println("1+2+...+10="+add2Ten());
}

public static int add2Ten()
{
int sum=0;
for(int i=1;i sum+=i;
return sum;
}
}

/* output-----
1+2+...+10=55
------------*/
// hw7_4,
public class hw7_4
{
public static void main(String args[])
{
int n=10;
System.out.println("1+2+...+"+n+"="+addto(n));
}

public static int addto(int n)
{
int sum=0;
for(int i=1;i sum+=i;
return sum;
}
}

/* output-----
1+2+...+10=55
------------*/
// hw7_5,
public class hw7_5
{
public static void main(String args[])
{
double c=20.0;

System.out.print("攝氏"+c+"度=華氏");
System.out.println(fahrenheit(c)+"度");
}

public static double fahrenheit(double c)
{
double f;

f=(9/5.0)*c+32;
return f;
}
}

/* output--------------
攝氏20.0度=華氏68.0度
---------------------*/
// hw7_6,
public class hw7_6
{
public static void main(String args[])
{
int n=6;

if(even(n))
System.out.println(n+"是偶數");
else
System.out.println(n+"不是偶數");
}

public static boolean even(int num)
{
if(num%2==0)
return true;
else
return false;
}
}

/* output---
6是偶數
----------*/
// hw7_7,
public class hw7_7
{
public static void main(String args[])
{
for(int i=1;i if(even(i) && i%9==0)
System.out.print(i+" ");
System.out.println();
}

public static boolean even(int num)
{
if(num%2==0)
return true;
else
return false;
}
}

/* output-------
18 36 54 72 90
--------------*/
// hw7_8,
public class hw7_8
{
public static void main(String args[])
{
int a=5,b=10;

System.out.println(a+"+"+b+"="+sum(a,b));
}

public static int sum(int a,int b)
{
return (a+b);
}
}

/* output-------
5+10=15
--------------*/
// hw7_9,
public class hw7_9
{
public static void main(String args[])
{
double r=2.0;

System.out.println("r="+r);
System.out.println("area="+area(r));
}

public static double area(double r)
{
final double PI=3.1415926;

return (PI*r*r);
}
}

/* output-------
r=2.0
area=12.5663704
--------------*/
// hw7_10,
public class hw7_10
{
public static void main(String args[])
{
int length=5,width=8;

System.out.print("length="+length);
System.out.println(", width="+width);
System.out.println("area="+area(length,width));
}

public static int area(int length,int width)
{
return (length*width);
}
}

/* output---------
length=5, width=8
area=40
----------------*/// hw7_11,
public class hw7_11
{
public static void main(String args[])
{
int arr[]={8,6,9,12,47,55,10};

for(int i=0;i System.out.print(arr[i]+" ");
System.out.println();

System.out.println("奇數有"+count(arr)+"個");
}

public static int count(int a[])
{
int sum=0;

for(int i=0;i if(a[i]%2==1)
sum++;
return sum;
}
}

/* output---------
8 6 9 12 47 55 10
奇數有3個// hw7_12,
public class hw7_12
{
public static void main(String args[])
{
int a[]={75,29,38,45,16};

for(int i=0;i System.out.print(a[i]+" ");
System.out.println();
System.out.println("最大值之索引值為["+max(a)+"]");
}

public static int max(int a[])
{
int m=a[0],index=0;

for(int i=0;i if(m {
m=a[i];
index=i;
}
return index;
}
}

/* output------------
75 29 38 45 16
最大值之索引值為[0]
-------------------*/
----------------*/

// hw7_13,
public class hw7_13
{
public static void main(String args[])
{
int a[][]={{75,29,10},{38,45,16}};

for(int i=0;i {
for(int j=0;j System.out.print(a[i][j]+" ");
System.out.println();
}
System.out.println("最大值為 "+max(a));
}

public static int max(int a[][])
{
int m=a[0][0];

for(int i=0;i for(int j=0;j if(m m=a[i][j];
return m;
}
}

/* output------------
75 29 10
38 45 16
最大值為 75
-------------------*/
// hw7_14,
public class hw7_14
{
public static void main(String args[])
{
int a[]={75,29,38,45,16};

for(int i=0;i System.out.print(a[i]+" ");
System.out.println();
System.out.println("最大值與最小值之差為"+diff(a));
}

public static int diff(int a[])
{
int max=a[0],min=a[0];

for(int i=0;i {
if(max max=a[i];
if(min>a[i])
min=a[i];
}
return (max-min);
}
}

/* output---------------
75 29 38 45 16
最大值與最小值之差為59
----------------------*/
// hw7_15,
public class hw7_15
{
public static void main(String args[])
{
int a[][]={{2,4,6},{1,3,5},{8,9}};

for(int i=0;i {
for(int j=0;j System.out.print(a[i][j]+" ");
System.out.println();
}
System.out.println("average="+avg(a));
}

public static double avg(int a[][])
{
int sum=0,len=0;

for(int i=0;i {
for(int j=0;j sum+=a[i][j];
len+=a[i].length; // 計算元素個數
}

return ((double)sum/len);
}
}

/* output------
2 4 6
1 3 5
8 9
average=4.75
-------------*/
// hw7_16,
public class hw7_16
{
public static void main(String args[])
{
int arr[][]={{1,2,3},{4,5,6},{7,8}};

System.out.println("平方前:");
show(arr);
square(arr);
System.out.println("\n平方後");
show(arr);
}

public static void square(int a[][])
{
for(int i=0;i {
for(int j=0;j a[i][j]*=a[i][j];
}
}

public static void show(int a[][])
{
for(int i=0;i {
for(int j=0;j System.out.print(a[i][j]+"\t");
System.out.println();
}
}
}

/* output-----------
平方前:
1 2 3
4 5 6
7 8

平方後
1 4 9
16 25 36
49 64
------------------*/
// hw7_17,
public class hw7_17
{
public static void main(String args[])
{
int n=10;
System.out.println("1+2+...+"+n+"="+add(n));
}

public static int add(int n)
{
if(n==1)
return 1;
else
return (n+add(n-1));
}
}

/* output-----------
1+2+...+10=55
------------------*/
// hw7_18a,
public class hw7_18a
{
public static void main(String args[])
{
System.out.println("fib(50)="+fib(50));
}

public static long fib(int n)
{
long f_1=1;
long f_2=1;
long f=0;
for(int i=3;i {
f=f_1+f_2;
f_2=f_1;
f_1=f;
}
return f;
}
}

/* output-----------
fib(50)=12586269025
------------------*/
// hw7_18b,
public class hw7_18b
{
public static void main(String args[])
{
System.out.println("fib(50)="+fib(50));
}

public static long fib(int n)
{
if (n==1 || n==2)
return 1;
else return fib(n-1)+fib(n-2);
}
}

/* output-----------
fib(50)=12586269025
------------------*/
// hw7_19,
public class hw7_19
{
public static void main(String args[])
{
int n=10;
long sum=0L;

for(int i=1;i sum+=fac(i);
System.out.println("1!+2!+...+"+n+"!="+sum);
}

public static long fac(int n)
{
if (n==0)
return 1;
else
return n*fac(n-1);
}
}

/* output--------------
1!+2!+...+10!=4037913
---------------------*/
// hw7_20,
public class hw7_20
{
public static void main(String args[])
{
System.out.print("梯形的上底為6,下底為8，高為3,");
System.out.println("面積為"+trapezoid(6,8,3));
System.out.print("梯形的上底為4.8,下底為3.7，高為2.5,");
System.out.println("面積為"+trapezoid(4.8f,3.7f,2.5f));
}

public static float trapezoid(int upper,int base,int height)
{
return ((upper+base)*height/2.0F);
}

public static float trapezoid(float upper,float base,float height)
{
return ((upper+base)*height/2.0F);
}
}

/* output----------------------------------------
梯形的上底為6,下底為8，高為3,面積為21.0
梯形的上底為4.8,下底為3.7，高為2.5,面積為10.625
-----------------------------------------------*/
// hw7_21,
public class hw7_21
{
public static void main(String args[])
{
System.out.println("abs(-6)="+abs(-6));
System.out.println("abs(-3.5f)="+abs(-3.5f));
System.out.println("abs(-2.123456789)="+abs(-2.123456789));
}

public static int abs(int n)
{
if(n return -n;
else return n;
}

public static float abs(float n)
{
if(n return -n;
else return n;
}

public static double abs(double n)
{
if(n return -n;
else return n;
}
}

/* output-------------------
abs(-6)=6
abs(-3.5f)=3.5
abs(-2.1234567)=2.123456789
--------------------------*/
// hw7_22,
public class hw7_22
{
public static void main(String args[])
{
System.out.println("rectangle(2,5)="+rectangle(2,5));
System.out.print("rectangle(2.3f,4.1f)=");
System.out.println(rectangle(2.3f,4.1f));
System.out.print("rectangle(8.92547,4.1357894)=");
System.out.println(rectangle(8.92547,4.1357894));
}

public static int rectangle(int length,int width)
{
return (length*width);
}

public static float rectangle(float length,float width)
{
return (length*width);
}

public static double rectangle(double length,double width)
{
return (length*width);
}
}

/* output---------------------------------------
rectangle(2,5)=10
rectangle(2.3f,4.1f)=9.429999
rectangle(8.92547,4.1357894)=36.913864216018005
----------------------------------------------*/
// hw7_23,
public class hw7_23
{
public static void main(String args[])
{
System.out.println("min(8,2)="+min(8,2));
System.out.println("min(1,5,9)="+min(1,5,9));
}

public static int min(int a,int b)
{
if(a>b)
return b;
else
return a;
}

public static int min(int a,int b,int c)
{
if(a return a;
else if(b return b;
else
return c;
}
}

/* output-----
min(8,2)=2
min(1,5,9)=1
------------*/