**3.21（科学：某天是星期几）泽勒一致性是由克里斯汀\LARGE \cdot泽勒开发的用于计算某天是星期几的算法。这个公式是： h = (q+(26(m+1)/10+k+k/4+j/4+5/j))%7
其中：
h是一个星期中的某一天（0为星期六；1为星期天；2为星期一；3为星期二；4为星期三；5为星期四；6为星期五）。 q是某月的第几天。 m是月份（3为三月，4为四月，……，12为十二月）。一月和二月分别记为上一年的13和14月。 j是year/100。 k是该世纪的第几年（即year0）。 注意：公式中的除法执行一个整数相除。编写程序，提示用户输入年、月、和该月的哪一天，然后显示它是一周中的星期几。
下面是一些运行示例：
Enter year:（e.g.，2012）: 2015
Enter month:1-12: 1
Enter the day of the month: 1-31: 25
Day of the week is Sunday
Enter year:（e.g.，2012）: 2012
Enter month:1-12: 5
Enter the day of the month: 1-31: 12
Day of the week is Saturday
**3.21(Science: day of the week) Zeller’s congruence is an algorithm developed by Christian Zeller to calculate the day of the week. The formula is h = (q+(26(m+1)/10+k+k/4+j/4+5/j))%7
where h is the day of the week (0: Saturday, 1: Sunday, 2: Monday, 3: Tuesday, 4: Wednesday, 5: Thursday, and 6: Friday). q is the day of the month. m is the month (3: March, 4: April, . . ., 12: December). January and February are counted as months 13 and 14 of the previous year. j is year / 100 k is the year of the century (i.e., year % 100). Note all divisions in this exercise perform an integer division. Write a program that prompts the user to enter a year, month, and day of the month, and displays the name of the day of the week.
Here are some sample runs: Enter year:（e.g.，2012）: 2015
Enter month:1-12: 1
Enter the day of the month: 1-31: 25
Day of the week is Sunday
Enter year:（e.g.，2012）: 2012
Enter month:1-12: 5
Enter the day of the month: 1-31: 12
Day of the week is Saturday
参考代码：
package chapter03; import java.util.Scanner; public class Code_21 { public static void main(String[] args) { int year, month, day, h, q, m, j, k; // Prompt the user to enter the year,the month and the day System.out.print("Enter year: (e.g.,2012):"); Scanner input = new Scanner(System.in); year = input.nextInt(); System.out.print("Enter month: 1-12:"); month = input.nextInt(); System.out.print("Enter the day of the month: 1-31:"); day = input.nextInt(); q = day; if(month == 1 || month == 2) { month += 12; year -= 1; } m = month; j = year / 100; k = year % 100; // Calculate the day of the week h = (q + (26 * (m + 1) / 10) + k + k / 4 + j / 4 + 5 * j) % 7; // Display the day of the week switch(h) { case 0: System.out.println("Day of the week is Saturday"); break; case 1: System.out.println("Day of the week is Sunday"); break; case 2: System.out.println("Day of the week is Monday"); break; case 3: System.out.println("Day of the week is Tuesday"); break; case 4: System.out.println("Day of the week is Wednesday"); break; case 5: System.out.println("Day of the week is Thursday"); break; case 6: System.out.println("Day of the week is Friday"); break; } input.close(); } } 结果显示： Enter year: (e.g.,2012):2015 Enter month: 1-12:1 Enter the day of the month: 1-31:25 Day of the week is Sunday Process finished with exit code 0