package test02.array;
import java.util.ArrayList;
import java.util.Arrays;
import com.sun.javafx.image.impl.IntArgb;
public class ArrayUtil {
public static void main(String[] args) {
// int[] arr={7, 9, 30, 3, 4};
// reverseArray(arr);
// int[] oldArr={1,3,4,5,0,0,6,6,0,5,4,7,6,7,0,5};
// removeZero(oldArr);
// int[] a1={3, 5, 7,8};
// int[] a2={4, 5, 6,7};
// merge(a1,a2);
// int[] a1={3, 5, 7,8};
// grow(a1, 3);
// fibonacci(15);
// getPrimes(23);
// getPerfectNumbers(4000);
int[] a={1,2,3,4};
join(a, "-");
}
/**
* 给定一个整形数组a , 对该数组的值进行置换
例如: a = [7, 9 , 30, 3] , 置换后为 [3, 30, 9,7]
如果 a = [7, 9, 30, 3, 4] , 置换后为 [4,3, 30 , 9,7]
* @param origin
* @return
*/
public static void reverseArray(int[] origin){
int[] newArr=new int[origin.length];
int j=0;
for (int i = origin.length-1; i >=0; i--) {
newArr[j++]=origin[i];
}
System.out.println(Arrays.toString(newArr));
}
/**
* 现在有如下的一个数组: int oldArr[]={1,3,4,5,0,0,6,6,0,5,4,7,6,7,0,5}
* 要求将以上数组中值为0的项去掉,将不为0的值存入一个新的数组,生成的新数组为:
* {1,3,4,5,6,6,5,4,7,6,7,5}
* @param oldArray
* @return
*/
public static int[] removeZero(int[] oldArray){
ArrayList<Integer> list=new ArrayList<>();
for (int i = 0; i < oldArray.length; i++) {
if (oldArray[i]!=0) {
list.add(oldArray[i]);
}
}
int[] newArr=new int[list.size()];
int j=0;
for (int i : list) {
newArr[j++]=i;
}
System.out.println(Arrays.toString(newArr));
return newArr;
}
/**
* 给定两个已经排序好的整形数组, a1和a2 , 创建一个新的数组a3, 使得a3 包含a1和a2 的所有元素, 并且仍然是有序的
* 例如 a1 = [3, 5, 7,8] a2 = [4, 5, 6,7] 则 a3 为[3,4,5,6,7,8] , 注意: 已经消除了重复
* @param array1
* @param array2
* @return
*/
public static int[] merge(int[] array1, int[] array2){
ArrayList<Integer> list=new ArrayList<>();
for (Integer arr1 : array1) {
list.add(arr1);
}
for (Integer arr2 : array2) {
if (!list.contains(arr2)) {
list.add(arr2);
}
}
int[] newArr=new int[list.size()];
int i=0;
for (int one : list) {
newArr[i++]=one;
}
for (int j = 0; j < newArr.length-1; j++) {
for (int k = 0; k < newArr.length-1-j; k++) {
if (newArr[k]>newArr[k+1]) {
int temp=newArr[k];
newArr[k]=newArr[k+1];
newArr[k+1]=temp;
}
}
}
System.out.println(Arrays.toString(newArr));
return newArr;
}
/**
* 把一个已经存满数据的数组 oldArray的容量进行扩展, 扩展后的新数据大小为oldArray.length + size
* 注意,老数组的元素在新数组中需要保持
* 例如 oldArray = [2,3,6] , size = 3,则返回的新数组为
* [2,3,6,0,0,0]
* @param oldArray
* @param size
* @return
*/
public static int[] grow(int [] oldArray, int size){
int[] newArr=new int[oldArray.length+size];
System.arraycopy(oldArray, 0, newArr, 0, oldArray.length);
System.out.println(Arrays.toString(newArr));
return newArr;
}
/**
* 斐波那契数列为:1,1,2,3,5,8,13,21...... ,给定一个最大值, 返回小于该值的数列
* 例如, max = 15 , 则返回的数组应该为 [1,1,2,3,5,8,13]
* max = 1, 则返回空数组 []
* @param max
* @return
*/
public static int[] fibonacci(int max){
if (max>1) {
ArrayList<Integer> list=new ArrayList<>();
list.add(1);
list.add(1);
while (list.get(list.size()-1)<max) {
if ((list.get(list.size()-1)+list.get(list.size()-2))<max) {
list.add(list.get(list.size()-1)+list.get(list.size()-2));
}else {
break;
}
}
int[] newArr=new int[list.size()];
int i=0;
for (int item : list) {
newArr[i++]=item;
}
System.out.println(Arrays.toString(newArr));
return newArr;
} else {
return null;
}
}
/**
* 返回小于给定最大值max的所有素数数组
* 例如max = 23, 返回的数组为[2,3,5,7,11,13,17,19]
* @param max
* @return
*/
public static int[] getPrimes(int max) {
ArrayList<Integer> list = new ArrayList<>();
for (int i = 2; i < max; i++) {
int j = 2;
while (j < i) {
// System.out.println("i:"+i+",j:"+j+",i%j:"+(i%j));
if (i%j==0) {
break;
}
j++;
}
if (j==i) {
list.add(i);
}
}
int[] newArr = new int[list.size()];
int i = 0;
for (int item : list) {
newArr[i++] = item;
}
System.out.println(Arrays.toString(newArr));
return newArr;
}
/**
* 所谓“完数”, 是指这个数恰好等于它的因子之和,例如6=1+2+3
* 给定一个最大值max, 返回一个数组, 数组中是小于max 的所有完数
* @param max
* @return
*/
public static int[] getPerfectNumbers(int max){
ArrayList<Integer> list = new ArrayList<>();
for (int i = 1; i < max; i++) {
int j = 1;
int sum=0;
while (j < i) {
// System.out.println("i:"+i+",j:"+j+",i%j:"+(i%j));
if (i%j==0) {
sum=sum+j;
}
j++;
}
if (sum==i) {
list.add(i);
}
}
int[] newArr = new int[list.size()];
int i = 0;
for (int item : list) {
newArr[i++] = item;
}
System.out.println(Arrays.toString(newArr));
return newArr;
}
/**
* 用seperator 把数组 array给连接起来
* 例如array= [3,8,9], seperator = "-"
* 则返回值为"3-8-9"
* @param array
* @param s
* @return
*/
public static String join(int[] array, String seperator){
String result=Arrays.toString(array).replace(" ", "").replace("[", "").replace("]", "").replace(",", seperator);
System.out.println(result);
return result;
}
}