package org.xukai.coderising.array;
import org.junit.Test;
public class ArrayUtilTest {
/**
* 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){
for (int i = 0; i < origin.length; i++) {
if (i == origin.length/2) {
break;
}
swap(origin,i,origin.length - 1 -i);
}
}
private void swap(int[] array,int a,int b){
array[a] = array[a] + array[b];
array[b] = array[a] - array[b];
array[a] = array[a] - array[b];
}
@Test
public void testReverseArray() {
int[] test = new int[]{7, 9, 30,-11, 3, 4};
reverseArray(test);
for (int i = 0; i < test.length; i++) {
System.out.println(test[i]);
}
}
/**
* 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 nullIndex = 0;
for (int i = 0; i < oldArray.length; i++) {
if (oldArray[i] != 0) {
nullIndex ++;
}
}
int[] newArray = new int[nullIndex];
nullIndex = 0;
for (int i = 0; i < oldArray.length; i++) {
if (oldArray[i] != 0) {
newArray[nullIndex] = oldArray[i];
nullIndex++;
}
}
return newArray;
}
@Test
public void removeZero() {
int[] test = new int[]{1,3,4,5,0,0,6,6,0,5,4,7,6,7,0,5};
int[] newArray = removeZero(test);
for (int i = 0; i < newArray.length; i++) {
System.out.println(newArray[i]);
}
}
/**
* 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){
int index_a = 0;
int index_b = 0;
int[] array = new int[array1.length + array2.length];
int i = 0 ;
while(index_a < array1.length && index_b < array2.length){
if (array1[index_a] < array2[index_b]) {
array[i] = array1[index_a];
index_a++;
i++;
} else if(array1[index_a] > array2[index_b]) {
array[i] = array2[index_b];
index_b++;
i++;
} else {
array[i] = array1[index_a];
i++;
index_a++;
index_b++;
}
}
if (index_a == array1.length) {
for (int j = index_b; j < array2.length; j++) {
array[i] = array2[j];
i++;
}
} else {
for (int j = index_a; j < array1.length; j++) {
array[i] = array1[j];
i++;
}
}
int[] result = new int[i];
System.arraycopy(array,0,result,0,i);
return result;
}
@Test
public void testMerge() {
int[] test1 = new int[]{2,3, 5, 7,8};
int[] test2 = new int[]{4, 5, 6,7,8,21,33};
int[] newArray = merge(test1,test2);
for (int i = 0; i < newArray.length; i++) {
System.out.println(newArray[i]);
}
}
/**
* 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[] newArray = new int[oldArray.length + size];
System.arraycopy(oldArray,0,newArray,0,oldArray.length);
return newArray;
}
@Test
public void testGrow() {
int[] test1 = new int[]{2,3, 5, 7,8};
int[] newArray = grow(test1, 5);
for (int i = 0; i < newArray.length; i++) {
System.out.println(newArray[i]);
}
}
/**
* 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){
if (max <= 1) {
return new int[0];
}
int index_a = 1;
int index_b = 1;
int temp = 0;
int count = 2;
while ((temp = index_a + index_b) < max) {
index_a = index_b;
index_b = temp;
count++;
}
int[] newArray = new int[count];
for (int i = count-1; i > -1 ; i--) {
newArray[i] = index_b;
temp = index_b - index_a;
index_b = index_a;
index_a = temp;
}
return newArray;
}
@Test
public void testfibonacci() {
int[] newArray = fibonacci(15);
for (int i = 0; i < newArray.length; i++) {
System.out.println(newArray[i]);
}
}
/**
* 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[] container = new int[5];
int count = 0;
for (int i = 3; i < max; i++) {
if (isShusu(i)) {
if (count == container.length) {
container = grow(container,container.length << 1);
}
container[count] = i;
count++;
}
}
int[] array = new int[count];
System.arraycopy(container,0,array,0,count);
return array;
}
@Test
public void testGetPrimes() {
int[] newArray = getPrimes(4);
for (int i = 0; i < newArray.length; i++) {
System.out.println(newArray[i]);
}
}
private boolean isShusu(int num){
int sqrt = 1;
while (sqrt * sqrt < num){
sqrt++;
}
for (int i = 2; i < sqrt; i++) {
if (num % i == 0) {
return false;
}
}
return true;
}
/**
* 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){
int[] container = new int[5];
int count = 0;
for (int i = 1; i < max; i++) {
if (isWanshu(i)) {
if (count == container.length) {
container = grow(container,container.length << 1);
}
container[count] = i;
count++;
}
}
int[] array = new int[count];
System.arraycopy(container,0,array,0,count);
return array;
}
@Test
public void testGetPerfectNumbers() {
int[] newArray = getPerfectNumbers(29);
for (int i = 0; i < newArray.length; i++) {
System.out.println(newArray[i]);
}
// isWanshu(6);
}
private boolean isWanshu(int num){
int sqrt = 1;
while (sqrt * sqrt < num){
sqrt++;
}
int sum = 1;
for (int i = 2; i < sqrt; i++) {
if (num % i == 0 ) {
sum = sum + i + (num/i);
}
}
if (sum == num) {
return true;
}
return false;
}
/**
* 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
* @return
*/
public String join(int[] array, String seperator){
String result = "";
for (int i = 0; i < array.length; i++) {
if (i != 0) {
result = result + seperator;
}
result = result + array[i];
}
return result;
}
@Test
public void testJoin() {
int[] test = {1, 5, 8, 4};
String seperator = "-";
String join = join(test, seperator);
System.out.println(join);
}
}