package com.johnChnia.coderising2017.array;
import com.johnChnia.coding2017.basic.queue.Queue;
import com.johnChnia.coding2017.basic.ArrayList;
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 length = origin.length;
for (int i = 0; i < length / 2; i++) {
int start = i;
int end = length - 1 - i;
int temp = origin[start];
origin[start] = origin[end];
origin[end] = temp;
}
}
/**
* 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) {
Queue notZeroQueue = new Queue();
for (int element :
oldArray) {
if (element != 0) {
notZeroQueue.add(element);
}
}
int[] newArray = new int[notZeroQueue.size()];
for (int index = 0; index < newArray.length; index++) {
newArray[index] = (int) notZeroQueue.remove();
}
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) {
ArrayList<Integer> array1List = new ArrayList<>();
for (int element :
array1) {
array1List.add(element);
}
for (int i = 0; i < array2.length; i++) {
int inserted = array2[i];
for (int j = 0; j < array1List.size(); j++) {
if (array1List.indexOf(inserted) != -1) {
break;
} else if (inserted < array1List.get(j)) {
array1List.add(j, inserted);
} else if (j == array1List.size() - 1) {
array1List.add(inserted);
}
}
}
int[] newArray = new int[array1List.size()];
for (int i = 0; i < array1List.size(); i++) {
newArray[i] = array1List.get(i);
}
return newArray;
}
/**
* 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) {
int[] copy = new int[oldArray.length + size];
System.arraycopy(oldArray, 0, copy, 0,
Math.min(oldArray.length, copy.length));
return copy;
}
/**
* 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[] newArray;
if (max == 1) {
newArray = new int[0];
} else if (max == 2) {
newArray = new int[]{1, 1};
} else {
int next;
ArrayList<Integer> arrayList = new ArrayList<>();
arrayList.add(1);
arrayList.add(1);
for (int i = 0; i < arrayList.size(); i++) {
next = arrayList.get(i) + arrayList.get(i + 1);
if (next < max) {
arrayList.add(next);
} else {
break;
}
}
newArray = new int[arrayList.size()];
for (int i = 0; i < arrayList.size(); i++) {
newArray[i] = arrayList.get(i);
}
}
return newArray;
}
/**
* 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) {
ArrayList<Integer> arrayList = new ArrayList<>();
for (int i = 0; i < max; i++) {
if (i <= 1) {
continue;
}
boolean flag = true;
for (int j = 2; j <= Math.sqrt(i); j++) {
if (i % j == 0) {
flag = false;
}
}
if (flag) {
arrayList.add(i);
}
}
int[] newArray = new int[arrayList.size()];
for (int i = 0; i < arrayList.size(); i++) {
newArray[i] = arrayList.get(i);
}
return newArray;
}
/**
* 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) {
ArrayList<Integer> arrayList = new ArrayList<>();
for (int i = 1; i < max; i++) {
int sum = 0;
for (int j = 1; j < i; j++) {
if (i % j == 0) {
sum += j;
}
}
if (sum == i) {
arrayList.add(i);
}
}
int[] newArray = new int[arrayList.size()];
for (int i = 0; i < arrayList.size(); i++) {
newArray[i] = arrayList.get(i);
}
return newArray;
}
/**
* 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 seperator
* @return
*/
public String join(int[] array, String seperator) {
StringBuilder stringBuilder = new StringBuilder();
for (int i = 0; i < array.length-1; i++) {
stringBuilder.append(array[i]);
stringBuilder.append(seperator);
}
stringBuilder.append(array[array.length-1]);
return stringBuilder.toString();
}
public void printArray(int[] array) {
for (int element :
array) {
System.out.print(element + ", ");
}
}
}