Day 6 (array example)

1、 Print Yang Hui triangle with two-dimensional array

class project {
    public static void main(String[] arg) {
        // Print a 10 Go Yanghui triangle 
        int[][] arr = new int[9][];
        for(int i =0; i<arr.length; i++){
            arr[i] = new int[i + 1];  // The first i Yes i+1 Elements 
            arr[i][0] = arr[i][i] =1; // The first and last elements are 1
            if (i>1){ // Start with the third line 
                for(int j = 1;j<arr[i].length-1;j++){
                    arr[i][j] = arr[i-1][j-1] + arr[i-1][j];
                }
            }
        }
        for (int i = 0; i<arr.length;i++){
            for (int j = 0;j<arr[i].length;j++){
                System.out.print(arr[i][j]+"\t");
            }
            System.out.println();
        }
    }
}

2、 Create a length of 6 Of int Type of the array , The required value is 1-30, At the same time, the element values are different

class project {
    public static void main(String[] arg) {
        int[] arr = new int[6];
        for (int i=0;i<arr.length;i++){
            arr[i] = (int)(Math.random()*30)+1;   //[0,1) [0,30) [1,31)
            for (int j=0;j<i;j++){
                if (arr[i]==arr[j]){
                    i--;  // return , Reassign 
                    break; // Go back to the first for Loop continuation i++, That is to regenerate random numbers 
                }
            }
        }
        for(int j = 0;j<arr.length;j++){
            System.out.println(arr[j]);
        }

    }
}

3、 Define a int One dimensional array of type , contain 10 Elements , Assign some random integers , Then find the maximum value of all elements , minimum value , Average , The sum of the , And output . requirement ： All random numbers are double digits

import java.util.Scanner;

class project {
    public static void main(String[] arg) {
        Scanner scan = new Scanner(System.in);
        int account = 0;
        float mean = 0l;
        int[] arr = new int[10];
        for (int i = 0; i<arr.length;i++){
            arr[i] = (int)(Math.random()*(90-10+1)+10); //[10,99]
            System.out.println(arr[i]);
        }

        int max = arr[0];
        for (int j = 0; j<arr.length;j++){
            if (max < arr[j]){
                max = arr[j];
            }
        }
        System.out.println("the max number of the arr is:"+max+"\n");
        int min = arr[0];
        for (int j = 0; j<arr.length;j++){
            if (min > arr[j]){
                min = arr[j];
            }
        }
        System.out.println("the min number of the arr is:"+min+"\n");
        for (int j = 0; j<arr.length;j++){
            account += arr[j];
            }
        System.out.println("the sum of the arr is:"+account+"\n");
        mean = account/arr.length;
        System.out.println("the avg of the arr is:"+mean+"\n");
        }
    }

4、 Linear search arr Element value specified in

class project {
    public static void main(String[] arg) {
        String[] arr = new String[]{"aa","bb","cc","dd","ee"};
        for (int i = 0; i<arr.length;i++){
            System.out.println(arr[i]);
        }
        String dest = "ee";
        boolean flag = true;
        for (int j = 0; j<arr.length; j++){
            if (dest.equals(arr[j])){  // stay arr[] Medium linear search and dest Equal element values , And return the index 
                System.out.println(" The specified value was found , Location is :"+j);
                flag = false;
                break;
            }
        }
        if (flag){
            System.out.println(" Did not find ");
        }
        }
    }