春夏秋冬
Scanner sc = new Scanner(System.in);
int a = sc.nextInt();
if (a == 1 || a == 2 || a == 12) {
System.out.println("冬天");
} else if (a == 3 || a == 4 || a == 5) {
System.out.println("春天");
} else if (a == 6 || a == 7 || a == 8) {
System.out.println("春天");
} else if (a == 8 || a == 9 || a == 10) {
System.out.println("秋天");
} else {
System.out.println("输入有误");
}
//第二种写法
Scanner sc = new Scanner(System.in);
int a = sc.nextInt();
switch(a){
case 12:
case 1:
case 2:
System.out.println("冬天");
break;
case 3:
case 4:
case 5:
System.out.println("春天");
break;
case 6:
case 7:
case 8:
System.out.println("夏天");
break;
case 9:
case 10:
case 11:
System.out.println("秋天");
break;
default:
System.out.println("出错了");
}
回文数
//回文数:12321,23432...
int count=0;
for(int a=10000;a<=100000;a++){
int ge=a%10;
int shi=a/10%10;
int bai=a/10/10%10;
int qian=a/10/10/10%10;
int wan=a/10/10/10/10%10;
if(ge==wan&&qian==shi){
System.out.println(a);
count++;
}
}
System.out.println("----------------");
System.out.println(count);
不死神兔
//方法一
int[] arr=new int[20];
arr[0]=1;
arr[1]=1;
int sum=0;
for(int a=2;a<arr.length;a++){
arr[a]=arr[a-1]+arr[a-2];
sum=arr[a];
//System.out.println(arr[a]);
}
System.out.println(sum);
//方法二
//规律:本月数量=上个月+上上个月
//第一个月=1,第二个月=1+0,第三个月=1+1;,第四个月=2+1.....
int one=1;
int two=1;
int sum=0;
for(int a=1;a<=18;a++){
sum=one+two;
two=one;
one=sum;
System.out.println(sum);
}
不死神兔出错原因
去掉最高最低求和
//5个数,去掉最高,去掉最低,求剩余数的平均数
int[] arr = { 1, 2, 3, 4, 5 };
// 取最大值=5
int max = arr[0];
for (int a = 0; a < arr.length; a++) {
if (max < arr[a]) {
max = arr[a];
}
}
System.out.println(max);
// 取最小值=1
int min = arr[0];
for (int a = 0; a < arr.length; a++) {
if (min > arr[a]) {
min = arr[a];
}
}
System.out.println(min);
System.out.println("---------------");
// 求和
int sum = 0;
for (int a = 0; a < arr.length; a++) {
//一开始我用||判断,但是会输出所有结果
//我的想法是1!=1,不满足,然后删掉,没考虑后面还有1!=5,这个是满足的,所以还是算满足条件,结果是输入1
//1!=1或1!=5,其实这个是满足的,所以不能用||来判断
//后来改成用&&判断,就能顺利删掉,1!=1且1!=5,不满足
if (arr[a] !=min && arr[a] !=max) {
sum += arr[a];
System.out.println(sum);
}
}
System.out.println("---------------");
System.out.println(sum / (arr.length - 2));
数组反转
int[] arr=new int[7];
//创建键盘录入
Scanner sc=new Scanner(System.in);
//for循环输入数字确定数组成员
for(int a=0;a<arr.length;a++){
System.out.println("no."+(a+1)+"number=");
arr[a]=sc.nextInt();
}
int kaishi=0;
int zuihou=arr.length-1;
//temp,临时的意思
int temp=0;
//第一种方法
for(kaishi=0,zuihou=arr.length-1;kaishi<=zuihou;kaishi++,zuihou--){
temp=arr[kaishi];
arr[kaishi]=arr[zuihou];
arr[zuihou]=temp;
System.out.println(arr[kaishi]);
}
↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑继续简化↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑
for (kaishi = 0; kaishi <= zuihou - kaishi; kaishi++) {
temp = arr[kaishi];
arr[kaishi] = arr[zuihou - kaishi];
arr[zuihou - kaishi] = temp;
System.out.println(arr[kaishi]);
}
System.out.println("--------");
//第二种方法
/* for (int i = 0; i < arr.length / 2; i++) {
temp = arr[i];
arr[i] = arr[arr.length - 1 - i];
arr[arr.length - 1 - i] = temp;
System.out.println(arr[i]);
}*/
for(int a=0;a<arr.length;a++){
System.out.println(arr[a]);
}
简单加密
// 创建键盘录入,输入4位整数
Scanner sc = new Scanner(System.in);
int[] arr=new int[4];
/* 第一步:先录入4位数 {4,5,6,7}
for(int a=0;a<arr.length;a++){
System.out.println("请输入第"+(a+1)+"位整数:");
int shuzi = sc.nextInt();
arr[a]=shuzi;
}*/
/* 第二步:每个数加上5 {9,10,11,12}
for(int a=0;a<arr.length;a++){
System.out.println("请输入第"+(a+1)+"位整数:");
int shuzi = sc.nextInt();
arr[a]=shuzi+5;
}*/
/* 第三步:对10取余,%10 {9,0,1,2}
for(int a=0;a<arr.length;a++){
System.out.println("请输入第"+(a+1)+"位整数:");
int shuzi = sc.nextInt();
arr[a]=(shuzi+5)%10;
}*/
//第四步:第一和第四,第二和第三互换位置 {2,1,0,9}
for(int a=0;a<arr.length;a++){
System.out.println("请输入第"+(a+1)+"位整数:");
int shuzi = sc.nextInt();
arr[a]=(shuzi+5)%10;
}
int kaishi=0;
int zuihou=arr.length-1;
for(kaishi=0;kaishi<zuihou-kaishi;kaishi++ ){
int temp=arr[kaishi];
arr[kaishi]=arr[zuihou-kaishi];
arr[zuihou-kaishi]=temp;
}
for(int a=0;a<arr.length;a++){
System.out.print(arr[a]);
}