[12] Java basics exercise

Posted by marcs910 on Thu, 13 Jan 2022 15:25:11 +0100

Weight loss plan (if)

Demand: enter the number of weeks and display the corresponding activities
Monday: running
Tuesday: swimming
Wednesday: jogging
Thursday: sleep
Friday: walk
Saturday: cycling
Sunday: Travel

Code demonstration

```public static void main(String[] args){
Scanner sc = new Scanner(System.in);
System.out.println("Please enter a weight loss plan for the day of the week:");
int Week = sc.nextInt();
if (Week>7||Week<1){
}
else if (Week==1){
System.out.println("run");
}
else if (Week==2){
System.out.println("Swimming");
}
else if (Week==3){
System.out.println("jogging");
}
else if (Week==4){
System.out.println("sleep");
}
else if (Week==5){
System.out.println("take a walk");
}
else if (Week==6){
System.out.println("ride a bike");
}
else{
System.out.println("Travel");
}
}
```

Weight loss plan (switch)

Demand: enter the number of weeks and display the corresponding activities
Monday: running
Tuesday: swimming
Wednesday: jogging
Thursday: sleep
Friday: walk
Saturday: cycling
Sunday: Travel

Code demonstration

``` public static void main(String[] args){
Scanner sc = new Scanner(System.in);
System.out.println("Please enter a weight loss plan for the day of the week:");
int Week = sc.nextInt();
switch (Week) {
case 1:
System.out.println("run");
break;
case 2:
System.out.println("Swimming");
break;
case 3:
System.out.println("jogging");
break;
case 4:
System.out.println("sleep");
break;
case 5:
System.out.println("take a walk");
break;
case 6:
System.out.println("ride a bike");
break;
case 7:
System.out.println("Travel");
break;
default:
System.out.println("Input error");
}
}
```

Every seven

Demand: start counting from any number. When the number reported contains 7 or a multiple of 7, it should be said that in order to make everyone familiar with the game, print out the number of 1-100 from the printing desk to meet the number of every seven

Code demonstration

```public static void main(String[] args){
for (int x = 1;x<=100;x++){
if (x%7==0||x%10==7||x/10%10==7){
System.out.print(x+" ");
}
}
}
```

Immortal rabbit

Demand: there is a pair of rabbits. From the third month after birth, a pair of rabbits are born every month. After the third month, a pair of rabbits are born every month. If the rabbits do not die, what are the logarithm of rabbits in the twentieth month?

Code demonstration

```public static void main(String[] args){
int[] arr = new int[20];
arr[0] = 1;
arr[1] = 1;
for (int x=2;x< arr.length;x++){
arr[x] = arr[x-2]+arr[x-1];
}
System.out.println("The number of rabbits in the 20th month is:"+arr[19]);
}
```

A hundred dollars and a hundred chickens

Demand: the mathematical problem put forward by the ancient mathematician Zhang Qiujian in the book Suanjing: the chicken Weng is worth five, the chicken mother is worth three, and the chicken chick is worth three. If you buy a hundred chickens for a hundred dollars, ask the chicken owner, the chicken mother and the chicken chick?

Code demonstration

```public static void main(String[] args){
for (int x = 0;x<=20;x++){
for (int y = 0;y<=33;y++){
int z=100-x-y;
if(z%3==0&&5*x+3*y+z/3 ==100){
System.out.println("cock:"+x+"   hen"+y+"    chick"+z);
}
}
}
}
```

Summation of array elements

Requirement: there is an array with elements {68, 27, 95, 88171996, 51210} Find the sum of elements that meet the requirements in the array. The requirements are: the single bit and ten bit of the summation element cannot be 7, and can only be an even number

Code demonstration

```public static void main(String[] args){
int[] arr = {68,27,95,88,171,996,51,210};
int sum = 0;
for (int i = 0;i<arr.length;i++){
int x =arr[i];
if (x%2==0&&x%10!=7&&x/10%10!=7){
sum=sum+x;
}
}
System.out.println("Elements and are:"+sum);
}
```

The contents of the array are the same

Requirement: design a method to compare whether two arrays are the same

Code demonstration

```public static void main(String[] args){
int[] arr = {11,22,44,44,55};
int[] arr2 = {11,22,33,44,55};
boolean m = compare(arr,arr2);
System.out.println(m);
}
public static boolean compare(int[] arr,int[] arr2){
if(arr.length!=arr2.length){
return false;
}
for (int x =0;x<arr.length;x++){
if (arr[x]!=arr2[x]){
return false;
}
}
return true;
}
```

lookup

An array arr={19, 28, 37, 46, 50} is known; Enter a data on the keyboard, find the index of the data in the array, and output the index value on the console

Code demonstration

```public static void main(String[] args){
int[] arr = {19,28,37,46,50};
Scanner sc = new Scanner(System.in);
int x= sc.nextInt();
int index= getChar(arr,x);
System.out.println("Index value="+index);
}
public static int getChar(int[] arr,int x){
int index = -1;
for (int i = 0;i< arr.length;i++){
if (x==arr[i]){
index = i;
break;
}
}
return index;
}
```

reversal

Requirement: an array arr = {19,28,37,46,50} is known; Exchange the elements in the array with a program
Array after exchange arr = {50,46,37,25,19}; And output the exchanged array on the console

Code demonstration

```public static void main(String[] args){
int[] arr = {19,28,37,46,50};
for (int start = 0,end = arr.length-1;start<=end;start++,end--){
int temp = arr[start];
arr[start]=arr[end];
arr[end]=temp;
}
printArray(arr);
}
public static void printArray(int[] arr){
System.out.print("[");
for (int x = 0;x< arr.length;x++){
if (x==  arr.length-1){
System.out.print(arr[x]);
}else{
System.out.print(arr[x]+",");
}
}
System.out.print("]");
}
```

Judges score

Requirements: Six judges will score, the score is an integer of 0-100, and the final score of the contestant is the average of the four scores after removing the highest score and the lowest score

Code demonstration

```public static void main(String[] args){
int[] arr=new int[6];
Scanner sc = new Scanner(System.in);
for (int i = 0;i< arr.length;i++){
arr[i] = sc.nextInt();
}
int max = getMax(arr);
int min = getMin(arr);
int sum = sum(arr);
int avg = (sum-max-min)/(arr.length -2) ;
System.out.println("The final score of the contestant is:"+avg);
}
public static int getMax(int[] arr){
int max = arr[0];
for (int x = 0;x< arr.length;x++){
if (arr[x]>max){
max = arr[x];
}
}
return max;
}
public static int getMin(int[] arr){
int min = arr[0];
for (int x = 0;x< arr.length;x++){
if (arr[x]<min){
min = arr[x];
}
}
return min;
}
public static int sum(int[] arr){
int sum = 0;
for (int i = 0;i< arr.length;i++){
sum = sum+arr[i];
}
return sum;
}
```

Topics: Java Back-end