day02--课后练习

编程题

1：计算付款金额: 一杯5元, 每两杯的第二杯半价(杯数由用户从键盘录入 ) 如: 5杯 = (5+2.5)*2 + 5 = 20

package homework;

import java.util.Scanner;

public class homework01 {
public static void main(String[] args) {
System.out.println("饮料一杯5元，每两杯的第二杯半价");
System.out.println("请输入您需要购买的饮料杯数");
Scanner scanner = new Scanner(System.in);
int a = scanner.nextInt();
int count = a % 2;
double sum = 0;
String result = "";
scanner.close();
if (count == 0) {
sum = (5 + 2.5) * (a / 2);
result = "(5+2.5)*" + a / 2 + "=" + sum;
}

else {
sum = (5 + 2.5) * (a / 2) + 5;
result = "(5+2.5)*" + a / 2 + "+5=" + sum;
}
System.out.println(result);
System.out.println(sum);

}
}

2:分别统计字符串”123456789012”奇数位及偶数位上的数字的和

将字符串的奇数位数字相加求和 c1 = 1 + 3 + 5 + 7 + 9 + 1

将字符串的偶数位数字相加求和 c2 = 2 + 4 + 6 + 8 + 0 + 2

package homework;

import java.util.Scanner;

public class homework02 {

public static void main(String[] args) {
System.out.println("本程序功能:统计字符串数字奇数位及偶数为上的数字的和");
System.out.println("请输入您需要统计的字符串数字");
Scanner scanner = new Scanner(System.in);
String s = scanner.next();
scanner.close();
int sum1 = 0, sum2 = 0;
String result1 = "", result2 = "";
char[] cs = s.toCharArray();
for (int i = 0; i < cs.length; i++) {
if (i % 2 == 0) {
sum1 += Integer.parseInt(cs[i] + "");
if (i == cs.length - 1) {
result1 = cs[i] + " " + result1;
} else {
result1 = cs[i] + "+" + result1;
}
} else {
sum2 += Integer.parseInt(cs[i] + "");
result2 = cs[i] + "+" + result2;
}

}
System.out.println(result1 + " =" + sum1);
System.out.println(result2 + " =" + sum2);

}

}

3：String[] cards = {“3”,”4”,”8”,”A”,”K”,”Q”}数组中存储了6张牌，设计一个算法把牌打乱，也就是实现洗牌功能

package homework;

import java.util.Random;

public class homework03 {
public static void check(int[] nums, int num) {
int i;
Random random = new Random();
for (i = 0; i < num; i++) {
if (nums[i] == nums[num]) {
nums[num] = random.nextInt(6);
check(nums, num);
}
}
if (i == num)
return;
}

public static void main(String[] args) {
System.out.println("本程序功能,实现洗牌功能");
String[] cards = { "3", "4", "8", "A", "K", "Q" };
Random random = new Random();
int[] copyCards = new int[cards.length];
for (int i = 0; i < cards.length; i++) {
copyCards[i] = random.nextInt(6);
check(copyCards, i);
System.out.print(cards[copyCards[i]]+" ");
}

}

}

4：一个5位的整数，判断它是不是回文数，例如12321是回文数

5：向一个有序的整型数组中插入一个数，插入后该数组还是有序的

(使用二分法)()