Merge pull request #9 from fzon0902/master

胡高清的作业

group27/815591664/2017Learning/.classpath

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+<?xml version="1.0" encoding="UTF-8"?>
+<classpath>
+	<classpathentry kind="src" path="src"/>
+	<classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER"/>
+	<classpathentry kind="con" path="org.eclipse.jdt.junit.JUNIT_CONTAINER/4"/>
+	<classpathentry kind="output" path="bin"/>
+</classpath>

group27/815591664/2017Learning/.gitignore

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+/bin/

group27/815591664/2017Learning/.project

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+<?xml version="1.0" encoding="UTF-8"?>
+<projectDescription>
+	<name>2017Learning</name>
+	<comment></comment>
+	<projects>
+	</projects>
+	<buildSpec>
+		<buildCommand>
+			<name>org.eclipse.jdt.core.javabuilder</name>
+			<arguments>
+			</arguments>
+		</buildCommand>
+	</buildSpec>
+	<natures>
+		<nature>org.eclipse.jdt.core.javanature</nature>
+	</natures>
+</projectDescription>

group27/815591664/2017Learning/.settings/org.eclipse.core.resources.prefs

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+eclipse.preferences.version=1
+encoding//src/com/coderising/array/ArrayUtil.java=UTF-8

group27/815591664/2017Learning/src/com/coderising/array/ArrayUtil.java

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+package com.coderising.array;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+
+import java.util.List;
+
+
+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 static void main(String[] args) {
+		int[] a = {7, 9, 30, 3, 4};
+		reverseArray(a);
+		System.out.println(Arrays.toString(a));
+
+
+		int oldArr[]={1,3,4,5,0,0,6,6,0,5,4,7,6,7,0,5,0} ;
+		System.out.println(Arrays.toString(removeZero(oldArr)));
+
+
+		int[] a1 = {3, 5, 7,8};
+		int[] a2 = {4, 5, 6,7};
+
+		System.out.println(Arrays.toString(merge(a1,a2)));
+
+
+		int[] b = { 2,3,6};
+		System.out.println(Arrays.toString(grow(b,5)));
+
+		System.out.println(genFibonacci(5));
+
+		System.out.println(Arrays.toString(fibonacci(30)));
+
+		System.out.println(Arrays.toString(getPrimes(10000)));
+
+		System.out.println(getFactor(10));
+
+		System.out.println(isPerfectNum(1000));
+
+//		System.out.println();
+		System.out.println(Arrays.toString(getPerfectNumbers(100)));
+
+		System.out.println(join(a,"&"));
+
+
+	}
+	public static void reverseArray(int[] origin){
+
+		if(origin.length==0){
+			return;
+
+		}
+		int[] copy = new int[origin.length];
+		System.arraycopy(origin, 0, copy, 0, origin.length);
+
+		for (int i = 0; i < copy.length; i++) {
+
+			origin[i] = copy[copy.length-1-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 static int[] removeZero(int[] oldArray){
+		int newSize = 0;
+		for (int i = 0; i < oldArray.length; i++) {
+			if(oldArray[i]!=0){
+				newSize++;
+			}
+		}
+		int index = 0;
+		int[] newArr = new int[newSize];
+		for (int i = 0; i < oldArray.length; i++) {
+			if(oldArray[i]!=0){
+				newArr[index] = oldArray[i];
+				index++;
+			}
+		}
+		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){
+		Arrays.sort(array1);
+		Arrays.sort(array2);
+
+		int[] newArr = new int[array1.length+array2.length];
+
+		System.arraycopy(array1, 0, newArr, 0,array1.length );
+		System.arraycopy(array2, 0, newArr, array1.length, array2.length);
+		Arrays.sort(newArr);
+		List<Integer> list = new ArrayList<Integer>();
+		for(int i=0;i<newArr.length;i++){
+
+			if(i==0){
+
+				list.add(newArr[i]);
+			}else{
+				if(newArr[i] != newArr[i-1]){
+					list.add(newArr[i]);
+
+				}
+			}
+		}
+//		Collections.sort(list);
+		System.out.println(list);
+		int[] target = new int[list.size()];
+		for(int i=0;i<list.size();i++){
+			target[i] = list.get(i);
+		}
+		return  target;
+	}
+	/**
+	 * 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);
+		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 == 0){
+			System.out.println("max必须大于或者等于1");
+			return null;
+		}else if(max ==1){
+			return new int[0];
+		}else{
+			List<Integer> list = new ArrayList<Integer>();
+			for(int i =0;i<max;i++){
+				int fib = genFibonacci(i);
+				if(fib<=max){
+					list.add(fib);
+				}
+			}
+
+			int[] newArr = new int[list.size()];
+			for (int i=0;i<list.size();i++) {
+				newArr[i] = list.get(i);
+
+			}
+			return newArr;
+		}
+	}
+
+
+	public static int genFibonacci(int index){
+
+		if(index<0){
+			System.out.println("索引不能为负数");
+			return -1;
+		}
+		if(index<=1){
+
+			return 1;
+		}else{
+			return genFibonacci(index-2)+genFibonacci(index-1);
+		}
+
+	}
+
+	/**
+	 * 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){
+		if(max<2){
+			return null;
+		}
+		List<Integer> list = new ArrayList<Integer>();
+		for(int i=2;i<=max;i++){
+			if(isPrime(i)){
+				list.add(i);
+			}
+		}
+
+		return listToArray(list);
+
+
+	}
+
+	public static int[] listToArray(List<Integer> list){
+		if(list == null){
+			return null;
+		}
+
+		int[] arr = new int[list.size()];
+
+		for(int i=0;i<list.size();i++){
+			arr[i] = list.get(i);
+
+		}
+		return arr;
+	}
+
+	/**
+	 * 某数是否为素数
+	 * @param num
+	 * @return
+	 */
+	public static boolean isPrime(int num){
+		if(num<=1){
+			return false;
+		}
+		boolean flag = true;
+		for(int i=2;i<num;i++){
+			if(num % i ==0){
+				flag = false;
+			}
+
+
+		}
+
+		return flag;
+	}
+
+	/**
+	 * 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){
+		List<Integer> list = new ArrayList<Integer>();
+		for(int i=1;i<=max;i++){
+			if(isPerfectNum(i)){
+				list.add(i);
+			}
+		}
+
+		return listToArray(list);
+	}
+
+
+	public static boolean isPerfectNum(int num){
+		if(num <=1){
+			return false;
+		}
+
+		List<Integer> factors = getFactor(num);
+		int sum = 0;
+		for (Integer integer : factors) {
+			sum = integer+sum;
+		}
+		if(sum == num){
+			return true;
+		}
+		return false;
+	}
+
+	public static List<Integer> getFactor(int num){
+		List<Integer> list = new ArrayList<Integer>();
+		list.add(1);
+
+
+		for(int i=2;i<num;i++){
+			if(num%i ==0){
+				list.add(i);
+			}
+		}
+//		list.add(num);
+
+		return list;
+	}
+	/*public static List<Integer> getFactor(int num){
+		List<Integer> list = new ArrayList<Integer>();
+		list.add(1);
+		int temp = num;
+		
+		while(!isPrime(temp)){
+			if(temp ==1){
+				break;
+			}
+			for(int i=2;i<=temp;i++){
+				if(temp % i ==0){
+					list.add(i);
+					temp = temp/i;
+					break;
+				}
+			}
+			
+		}
+		list.add(temp);
+		
+		return list;
+	}*/
+
+	/**
+	 * 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){
+		StringBuilder sb = new StringBuilder();
+		for (int i : array) {
+			sb.append(i);
+			sb.append(seperator);
+
+		}
+
+		return sb.subSequence(0, sb.length()-1).toString();
+	}
+
+
+}