冒泡排序`交换排序·二分查找

雨点打透心脏的1/2处 2022-08-08 12:51 128阅读 0赞

public class ArrayTest \{  
public static void main(String\[\] args) \{  
int\[\] a = new int\[\] \{1,2,3\};  
int \[\] b = new int\[4\];  
System.arraycopy(a,0,b,0,4);  
for(int i = 0;i<b.lentth;i++) \{  
System.out.println(b\[i\]);  
\}  
\}  
\}  
  
  
  
  
三维数组。type\[\]\[\]\[\] a = new type\[2\]\[3\]\[4\];  
  
  
public class ArrayTest \{  
poublic static void main(String\[\] args) \{  
int \[\]\[\]\[\] a =new int\[2\]\[3\]\[4\];  
System.out.println(a instanceof int\[\]\[\]\[\]);  
System.out.println(a instanceof object);  
  
  
System.out.println(a\[0\] instanceof int\[\]\[\]);  
  
  
System.out.println(a\[0\]\[0\] instanceof int\[\]);  
  
  
for(int i = 0; i<a.length; i++) \{  
for (int j = 0;j <a\[i\].length;j++)\{  
for(int k = 0;k <a\[i\]\[j\].length;k++)\{  
a\[i\]\[j\]\[k\] = 100;  
\}  
\}  
\}  
\}  
\}  
  
  
  
  
  
  
  
  
冒泡排序： （掌握交换排序，快速排序的原理与实现方式）  
  
  
  
  
  
  
public class BubbleSortTest \{  
public static void bubbleSort(int\[\] array)\{  
for(int i = 0;i < array.length - 1; i++) \{  
for(int j = 0;j < array.length - i - 1;j++) \{  
if(array\[j\] > array\[j+1\]) \{  
int temp = array\[j\];  
array\[j\] = array\[j+1\];  
array\[j+1\]= temp;  
\}  
\}  
  
System.out.println("第" + (i + 1) + "次排序");  
for(int k = 0; k < array.length; k++) \{  
System.out.print(array\[k\] + " ");  
\}  
System.out.println();  
\}  
\}  
public static void main(String\[\] args) \{  
int\[\] array = \{4,9,2,8,6,1\};  
bubbleSort(array);  
\}  
\}  
  
  
  
  
int\[\] a = new int\[10\];  
int\[\] a = \{new int\[\]\}\{1,2,3,4,5,6\}  
数组的属性 length是public final int的，一旦确定不能改变。  
  
二维数组是一种平面的二维结构  
int\[\]\[\] a = new int\[2\]\[3\];  
第一个方括号里代表行，第二个代表列  
  
三维数组  
int\[\]\[\]\[\] a = new type\[2\]\[3\]\[4\];  
  
  
  
  
二分查找（Binary Search）:待查找的数组要有序  
import java.util.Random;  
public class RandomTest \{  
public static void main(String\[\] args) \{  
Random random = new Random();  
for(int i = 0;i < 50;i++)\{  
//System.out.println(random.nextInt(41)+10);  
//\}  
double result = Math.random();  
result \*= 41;  
int result2 = (int)result;  
result2+= 10;  
System.out.println(result2);  
\}  
\}  
  
  
  
  
  
  
import java.util.Random;  
public class RandomTest \{  
public static void main(String\[\] args) \{  
int\[\] count = new int\[41\];  
Random random = new Random();  
for(int i = 0; i<50;i++)\{  
int number = random.nextInt(41)+ 10;  
count \[number -10\]++;  
\}  
for(int i = 0; i<count.length; i++) \{  
  
\}  
\}  
\}