# Untitled

unknown
java
24 days ago
2.1 kB
4
Indexable
Never
```
/*

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));

}
}
```