ch04 Programming Exercise
1.
1 /**
2 * File: Ex4_1.java
3 * ----------------
4 * This program is to generate the lyrics .
5 *
6 * @author Administrator
7 *
8 */
9 import acm.program.*;
10
11 public class Ex4_1 extends ConsoleProgram {
12
13 public void run() {
14
15 for (int i=n; i>0; i--){
16 println(i + " bottles of beer on the wall.");
17 println(i + " bottles of beer.");
18 println("You take one down, pass it around.");
19 println(i-1 + " bottles of beer on the wall.");
20 println();
21 }
22
23 }
24
25 private static final int n = 99;
26
27
28 }
2.
1 /**
2 * File: Ex4_2.java
3 * ----------------
4 * This program also write a silly song.
5 *
6 * @author Administrator
7 *
8 */
9
10 import acm.program.*;
11
12 public class Ex4_2 extends ConsoleProgram {
13
14 public void run() {
15
16 for (int i=1; i<11; i++) {
17 println("This old man, he played " + i + ".");
18 println("He played knick-knack on my ");
19 switch(i){
20 case 1: println("thumb"); break;
21 case 2: println("shoe"); break;
22 case 3: println("knee"); break;
23 case 4: println("door"); break;
24 case 5: println("hive"); break;
25 case 6: println("sticks"); break;
26 case 7: println("up to heaven"); break;
27 case 8: println("pate"); break;
28 case 9: println("spine"); break;
29 case 10: println("shin"); break;
30 default: break;
31 }
32
33 println("With a knick-knack, paddy-whack.");
34 println("Give you dog a bone.");
35 println("This old man came roling home.");
36 println();
37
38 }
39 }
40
41
42 }
3.
1 /**
2 * File: Ex4_3.java
3 * ----------------
4 * This program reads in a positive integer N and then calculates and
5 * displays the sum of the first N odd integers.
6 *
7 * @author Administrator
8 *
9 */
10
11 import acm.program.*;
12
13 public class Ex4_3 extends ConsoleProgram {
14
15 public void run() {
16
17 int sum = 0;
18 int n = 1;
19
20 int N = readInt("Enter N: ");
21 for (int i=0; i<N; i++) {
22 sum += n;
23 n += 2;
24 }
25 println("sum = " + sum);
26
27 }
28
29 }
4.略。
5.
1 /**
2 * File: Ex4_5.java
3 * ----------------
4 * This program display the integers between 1 and 100 that are
5 * divisible by either 6 or 7 but not both.
6 *
7 * @author Administrator
8 *
9 */
10
11 import acm.program.*;
12
13 public class Ex4_4 extends ConsoleProgram {
14
15 public void run() {
16 for (int i=1; i<=100; i++){
17
18 if((i%6==0 || i%7==0)&&(i%42!=0)){
19 println(i);
20 }
21 }
22 }
23
24 }
6.略。
7.
1 /**
2 * File: Ex4_7.java
3 * ----------------
4 * This program reverse the order of the integer.
5 *
6 * @author Administrator
7 *
8 */
9
10 import acm.program.*;
11
12 public class Ex4_7 extends ConsoleProgram {
13
14 public void run() {
15 println("This program reverse the digits in an intger.");
16 int n = readInt("Enter a positive integer: ");
17 int rn = 0;
18 while (n>0){
19 rn = rn*10 + n%10;
20 n /=10;
21 }
22 println("The reversed number is " + rn);
23 }
24
25 }
8.
1 /**
2 * File: Ex4_8.java
3 * ----------------
4 * This program counts backwards from the value START
5 * to zero, as in the countdown preceding a rocket
6 * launch.
7 *
8 * @author Administrator
9 *
10 */
11
12 import acm.program.*;
13
14 public class Ex4_8 extends ConsoleProgram {
15
16 private static final int START = 10;
17
18 public void run() {
19 int t = START;
20 while ( t>=0){
21 println(t);
22 t--;
23 }
24 println("Liftoff!");
25 }
26
27 }
9.
1 /**
2 * File: Ex4_9.java
3 * ----------------
4 * Fibonacci sequence.
5 *
6 * @author Administrator
7 *
8 */
9
10 import acm.program.*;
11
12 public class Ex4_9 extends ConsoleProgram {
13
14 public void run(){
15
16 int n1 = 0;
17 int n2 = 1;
18 int n = 0;
19 int i = 2;
20
21 println("F0 = " + n1);
22 println("F1 = " + n2);
23
24 while(n<10000){
25 n = n1 + n2;
26 println("F" + i + " = " + n);
27 n1 = n2; //Fn = Fn-1 + Fn-2
28 n2 = n;
29 i++;
30 }
31
32 }
33
34 }
10.略
11. 这里要画个8x8的棋盘，方格放置简单，放圆有点困难，看图总结，啥时候放圆。
1 /**
2 * File: Ex4_11.java
3 * -----------------
4 * checkboard
5 *
6 * @author Administrator
7 *
8 */
9 import acm.graphics.*;
10 import acm.program.*;
11
12 public class Ex4_11 extends GraphicsProgram {
13 public void run(){
14 for (int i=0; i<8; i++){
15 for(int j=0; j<8; j++){
16 add(new GRect(i*20, j*20, 20, 20));
17 if(((j%2==0)&&(i%2!=0))||((j%2!=0)&&(i%2==0))){
18 add(new GOval(i*20, j*20, 20, 20));
19
20 }
21 }
22 }
23
24 }
25
26 }
12. 简单的日历，画表简单，就是放格子，加数字有点困难。
1 /**
2 * File: Ex4_12.java
3 * -----------------
4 * calendar.
5 *
6 * @author Administrator
7 *
8 */
9 import acm.graphics.*;
10 import acm.program.*;
11
12 public class Ex4_12 extends GraphicsProgram {
13 public void run() {
14 int rows = (DAYS_IN_MONTH + DAY_MONTH_STARTS) / 7;
15 if ((DAY_MONTH_STARTS + DAYS_IN_MONTH) % 7 != 0){
16 rows++;
17 }
18
19 for (int i = 0; i < rows; i++) {
20 int y = i * DAY_HEIGHT;
21
22 for (int j = 0; j < 7; j++) {
23 int x = j * DAY_WIDTH;
24
25 add(new GRect(x, y, DAY_WIDTH, DAY_HEIGHT));
26
27 int date = (((7 * i) + j) - DAY_MONTH_STARTS) + 1;
28
29 if (date > 0 && date <= DAYS_IN_MONTH) {
30 add(new GLabel("" + date + ".", x + 5, y + 15));
31 }
32
33 }
34 }
35 }
36
37 // The number of days in the month
38 private static final int DAYS_IN_MONTH = 31;
39
40 // The day of the week on which the month starts
41 // Sunday = 0, Monday = 1, ...
42 private static final int DAY_MONTH_STARTS = 5;
43
44 // The width in pixels of a day on the calendar
45 private static final int DAY_WIDTH = 40;
46
47 // The height in pixels of a day on the calendar
48 private static final int DAY_HEIGHT = 30;
49
50
51 }