Untitled

/*

nested for-loop:

outer loop（外面的循环): the number of rows (循环行数)
inner loop (里面的循环): the number of columns (循环列数)


Array
create an integer array:   

int[] array_name = new int[length];
int[] arr2 = {4, 6, -3, 23, 1, 5, -1, -4, 100};

**The length of array is FIXED

**Index is used to access/modify array element (用索引(index) 来提取、改变某一个信息)

index：0 ~ （length-1).         索引从 0  开始， 到 （array 长度 - 1） 停止



*/

import java.util.*;
import java.lang.Math;
public class Main
{
	public static void main(String[] args) {
		
		/*
		     *
		    ***
		   *****
		  *******
		 *********
		***********

		*/
		
		//只需要打符号前面的空格，不需要打后面的

//Solution:

		for(int i=0; i < 6; i++) {
		    for(int j = 5; j > i; j--) {
		        System.out.print(' ');
		    }
		    for(int j = 0; j < (i*2+1); j++) {
		        System.out.print('*');
		    }
		    System.out.println();
		}
		
		
		//create an int array of size 10 with numbers of 1 to 10 in increasing order
		int N = 20;
		int[] arr = new int[N];

        for(int i = 0; i < N; i++) {
            arr[i] = i+1;
        }
        
        
        // find the minimum value in the Arrays
        
        // find the current minimum and compare with the current number
        
        N = 9;
        int[] arr2 = {4, 6, -3, 23, 1, 5, -1, -4, 100};
        
        int current_smallest = arr2[0];
        for(int i = 0; i < N; i++) {
            if(current_smallest > arr2[i]) {
                current_smallest = arr2[i];
            }
            System.out.println(current_smallest);
        }
        
        
        //create an array, where the ith number stores the value of 2^i, 0 <= i <= N-1
        N = 15;
        int[] arr3 = new int[N];
        for(int i = 0; i < N; i++)
        {
            int product = 1;
            for(int j = 0; j < i; j++) {
                product *= 2;
            }
            arr3[i] = product;
        }
        
		System.out.println(Arrays.toString(arr3));
		
	}
}