package com.coderising.array;
import java.util.HashSet;
import java.util.Set;
public class ArrayUtil {
/**
* 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 void reverseArray(int[] origin){
int temp;
for (int i=0;i<origin.length/2;i++) {
temp = origin[i];
origin[i] = origin[origin.length-i-1];
origin[origin.length-i-1] = temp;
}
for(int i=0; i<origin.length;i++){
System.out.print(origin[i]+",");
}
System.out.print("\n");
}
/**
* 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 int[] removeZero(int[] oldArray){
int count = 0;
for(int i=0;i<oldArray.length; i++){
if(oldArray[i]!=0){
count += 1;
}
}
int [] newArray = new int [count];
int i = 0;
for(int j=0;j<oldArray.length;j++){
if(oldArray[j]!=0){
newArray[i] = oldArray[j];
i += 1;
}
}
for (int a : newArray) {
System.out.print(a+",");
}
System.out.print("\n");
return newArray;
}
/**
* 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 int[] merge(int[] array1, int[] array2){
//构造一个合并后无排序的包含重复元素的数组
int length = array1.length + array2.length;
int[] array_merge = new int[length];
for (int i = 0; i < array1.length; i++) {
array_merge[i] = array1[i];
}
for (int i = array1.length; i < array_merge.length; i++) {
array_merge[i] = array2[i-array1.length];
}
//打印合并后无序数包含重复元素的数组
System.out.print(array_merge[0]);
for (int j = 0; j < array_merge.length; j++) {
System.out.print(","+array_merge[j]);
}
System.out.print("\n");
//将合并的元素去重复
Set<Integer> x = new HashSet<>();
for (int i = 0; i < array_merge.length; i++) {
x.add(array_merge[i]);
}
Integer[] arr = x.toArray(new Integer[x.size()]);
//进行排序，采用插入排序
for (int i = 0; i < arr.length; i++) {
for (int j = i+1; j < arr.length; j++) {
if (arr[i]>arr[j]) {
int tmp = arr[i];
arr[i] = arr[j];
arr[j] = tmp;
}
}
}
int[] array_merger = new int[arr.length];
for (int i = 0; i < arr.length; i++) {
array_merger[i] = arr[i].intValue();
}
for (int i : array_merger) {
System.out.println(i);
}
return array_merger;
}
/**
* 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 int[] grow(int [] oldArray, int size){
//确定数组的长度
int length = oldArray.length + size;
int[] newArray = new int [length];
//对数组的原有元素进行赋值
for (int i = 0; i < oldArray.length; i++) {
newArray[i] = oldArray[i];
}
//对扩容的元素进行赋值为0的操作
for (int i = oldArray.length; i < newArray.length; i++) {
newArray[i] = 0;
}
//打印数组
System.out.print(newArray[0]);
for (int j = 1; j < newArray.length; j++) {
System.out.print(","+newArray[j]);
}
System.out.print("\n");
return newArray;
}
/**
* 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 int[] fibonacci(int max){
int a = 1, b = 1, count = 0;
int c = 2;
while(c<max){
c = a + b;
a = b;
b = c;
count += 1;
}
System.out.println(count);
int [] array = new int [count+1];
if (max == 1) {
return null;
} else {
array[0] = 1;
array[1] = 1;
for (int i = 2; i < array.length; i++) {
array[i] = array[i-1] + array[i-2];
}
for (int i : array) {
System.out.println(i);
}
return array;
}
}
/**
* 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 int[] getPrimes(int max){
int number = 2, count = 0, b = 0;
//获取列表的长度
while(number<max){
boolean a = true;
for (int i = 2; i < number; i++) {
if(number%i==0){
a = false;
}
}
if(a == true){
count += 1;
}
number += 1;
}
System.out.println(count);
//给列表中的元素进行赋值
int [] array = new int [count];
int counter = 0, num=2;
while (counter<count) {
boolean a = true;
for (int i = 2; i < num; i++) {
if(num%i==0){
a = false;
}
}
if(a == true){
array[counter] = num;
counter += 1;
}
num ++;
}
for (int i : array) {
System.out.println(i);
}
return array;
}
/**
* 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 int[] getPerfectNumbers(int max){
//先计算出小于max的所有完数的个数
int count=0, number=1, sum=0;
while(number<max){
for (int i = 1; i < number; i++) {
if(number%i==0){
sum += i;
}
}
if(sum==number){
count += 1;
}
sum = 0;
number += 1;
}
int[] perfect_array = new int[count];
int index = 0, num=1, sum1;
while(num<max){
sum1 = 0;
for (int i = 1; i < num; i++) {
if(num%i==0){
sum1 += i;
}
}
if(sum1==num){
perfect_array[index] = num;
index+=1;
}
num += 1;
}
for (int i : perfect_array) {
System.out.println(i);
}
return perfect_array;
}
/**
* 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 String join(int[] array, String seperator){
String[] str = new String[array.length];
for (int i = 0; i < str.length; i++) {
str[i] = String.valueOf(array[i]);
}
String a=str[0];
for (int i = 1; i < str.length; i++) {
a = a + seperator+str[i];
}
System.out.print(a+"\n");
return a;
}
}
class ArrayTest{
public static void main(String[] args){
ArrayUtil array = new ArrayUtil();
int [] list = {7, 9, 30, 3, 4};
array.reverseArray(list);
System.out.println("----reverseArray---end----");
ArrayUtil oldArray = new ArrayUtil();
int [] arrays = {1,3,4,5,0,0,6,6,0,5,4,7,6,7,0,5};
oldArray.removeZero(arrays);
System.out.println("----removeZero-----end----");
ArrayUtil array_merge = new ArrayUtil();
int [] array1 = {3, 5, 7, 8};
int [] array2 = {1, 3, 10, 100};
array_merge.merge(array1, array2);
System.out.println("----merge----------end----");
ArrayUtil growArray = new ArrayUtil();
int [] garray = {1,3,4};
growArray.grow(garray, 10);
System.out.println("----grow-----------end---");
ArrayUtil fib = new ArrayUtil();
fib.fibonacci(100);
System.out.println("----fib------------end---");
ArrayUtil sushu = new ArrayUtil();
sushu.getPrimes(100);
System.out.println("----getPrimes------end----");
ArrayUtil perfectnumber = new ArrayUtil();
perfectnumber.getPerfectNumbers(30);
System.out.println("----getPerfectNumbers---end-----------");
ArrayUtil string_format = new ArrayUtil();
int[] a = {1,2,3,4,5,6,7,45,45,768};
string_format.join(a, "$");
System.out.println("----string_format------end---");
}
}