Java算法求最大最小值,倒序,冒泡排序,斐波纳契数列，日历一些经典算法

一，求最大，最小值

int[] a={21,31,4,2,766,345,2,34};
//这里防止数组中有负数，所以初始化的时候给的数组中的第一个数。
int max=a[0];
int min=a[0];
for (int i = 0; i < a.length; i++) {
     if(a[i]>max)
             max=a[i];
     if(a[i]<min)
             min=a[i];
}
System.out.println("最大的数是："+max);
System.out.println("最小的值是："+min);

二，1--100之间的质数(什么叫质数，就是只能被1和本身能除尽的数)

for (int i = 2; i <= 100; i++) {
    boolean flag = true;
    for (int j = 2; j < i/2+1; j++) {
         if(i%j==0){
              flag = false;
              break;
         }
     }
     if(flag){
         System.out.print(i+" ");
     }
}

三，输入一个字符串，倒着打印出来（如：abcdefg1256，打印出来是：6521gfedcba）

Scanner scanner = new Scanner(System.in);
String ss = scanner.next();
char[] a = ss.toCharArray();
char tmp = 0;
for(int i = 0; i<a.length/2;i++){
    tmp = a[i];
    a[i]=a[a.length-i-1];
    a[a.length-i-1]=tmp;
}
String s=new String(a);
System.out.println(s);

四，斐波纳契数列(0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597 2584 4181)

int a=0;
int b=1;
for (int i = 1; i <= 10; i++) {
      System.out.print(a+" ");
      a=a+b;
      System.out.print(b+" ");
      b=a+b;
}

五，冒泡排序

int score[] = {167,69,75,87,89,90,99,100,54,62,87,201,89,14,25,57,53,19 };
for (int i = 0; i < score.length; i++) {
     for (int j = i; j < score.length; j++) {
          if (score[i] > score[j]) {
               int temp = score[i];
               score[i] = score[j];
               score[j] = temp;
          }
     }
}
System.out.print("最终排序结果：");
for (int a = 0; a < score.length; a++) {
    System.out.print(score[a] + " ");
}

六，在控制台打印日历，平且标出今天

package test;
import java.text.DateFormatSymbols;
import java.util.Calendar;
import java.util.GregorianCalendar;  

public class HelloString {
        public static void main(String[] args) {
            // 构建D为当前日期
            GregorianCalendar d = new GregorianCalendar();  

            int today = d.get(Calendar.DAY_OF_MONTH);
            int month = d.get(Calendar.MONTH);  

            // D组为本月的开始日期
            d.set(Calendar.DAY_OF_MONTH, 1);  

            int weekday = d.get(Calendar.DAY_OF_WEEK);  

            // 一周的第一天是星期日
            int firstDayOfWeek = d.getFirstDayOfWeek();  

            int indent = 0;
            while (weekday != firstDayOfWeek) {
                indent++;
                d.add(Calendar.DAY_OF_MONTH, -1);
                weekday = d.get(Calendar.DAY_OF_WEEK);
            }  

            // 打印工作日的名称
            String[] weekdayNames = new DateFormatSymbols().getShortWeekdays();
            do {
                System.out.printf("%4s", weekdayNames[weekday]);
                d.add(Calendar.DAY_OF_MONTH, 1);
                weekday = d.get(Calendar.DAY_OF_WEEK);
            } while (weekday != firstDayOfWeek);
            System.out.println();  

            for (int i = 1; i <= indent; i++)
                System.out.print("    ");  

            d.set(Calendar.DAY_OF_MONTH, 1);
            do {
                // 打印的一天
                int day = d.get(Calendar.DAY_OF_MONTH);
                System.out.printf("%3d", day);  

                // 带*标记当前日期
                if (day == today)
                    System.out.print("*");
                else
                    System.out.print(" ");  

                // 先进的第二天
                d.add(Calendar.DAY_OF_MONTH, 1);
                weekday = d.get(Calendar.DAY_OF_WEEK);  

                // 从本周开始新的一行
                if (weekday == firstDayOfWeek)
                    System.out.println();
            } while (d.get(Calendar.MONTH) == month);
            // 循环退出时，D是下个月的1天  

            // 如果需要打印的最终行
            if (weekday != firstDayOfWeek)
                System.out.println();
        }
}