Merge pull request #13 from GZ-RXP/master

20170226 assignment:ArrayUtil and litestructs

group11/283091182/src/com/coderising/array/ArrayUtil.java

@@ -0,0 +1,303 @@
+package com.coderising.array;
+
+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){
+		if(origin==null||origin.length==0){
+			throw new RuntimeException("invalid array argument!");
+		}
+		if(origin.length>1){
+			int temp;
+			for(int i=0;i<origin.length/2;i++){
+				temp = origin[i];
+				origin[i] = origin[origin.length-1-i];
+				origin[origin.length-1-i]= 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){
+		if(oldArray==null || oldArray.length==0){
+			return oldArray;
+		}else{
+			int[] tmp = new int[oldArray.length];
+			int pos = 0;
+			for(int i=0;i<oldArray.length;i++){
+				if(oldArray[i]!=0){
+					tmp[pos]=oldArray[i];
+					pos++;
+				}
+			}
+			int[] result = new int[pos];
+			System.arraycopy(tmp, 0, result, 0, pos);
+			return result;
+		}
+	}
+
+	/**
+	 * 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){
+		//Check array sorting
+		checkIfArraySortedAsc(array1);
+		checkIfArraySortedAsc(array2);
+		//both are null then return null
+		if(array1==null && array2==null){
+			return null;
+		}
+		//one of them is empty array then return another
+		//Scenario:array1 is empty
+		if(array1.length==0){
+			if(array2 == null){
+				return array1;
+			}else{
+				return array2;
+			}
+		}else{
+			//Scenario:array1 is not empty
+			if(array2.length==0){
+				return array1;
+			//Scenario: both array1 and array2 are not empty
+			}else{
+				//Do merge in this case
+				int[] array3 = new int[array1.length+array2.length];
+				int pos1=0;
+				int pos2=0;
+				int pos3=0;
+				while(pos1<array1.length || pos2<array2.length){
+					if(pos1==array1.length){
+						array3[pos3] = array2[pos2];
+						pos2++;
+						pos3++;
+						continue;
+					}
+					if(pos2==array2.length){
+						array3[pos3] = array1[pos1];
+						pos1++;
+						pos3++;
+						continue;
+					}
+					if(array1[pos1]>array2[pos2]){
+						array3[pos3]=array2[pos2];
+						pos2++;
+						pos3++;
+					}else if(array1[pos1]<array2[pos2]){
+						array3[pos3]=array1[pos1];
+						pos1++;
+						pos3++;
+					}else{
+						array3[pos3]=array1[pos1];
+						pos1++;
+						pos2++;
+						pos3++;
+					}
+
+				}
+				array3 = removeZero(array3);
+				printArray("Merge result=",array3);
+				return array3;
+			}
+		}
+	}
+	private void checkIfArraySortedAsc(int[] arr){
+		if(arr==null||arr.length==0||arr.length==1){
+			return;
+		}else{
+			for(int i=1;i<arr.length;i++){
+				if(arr[i]<arr[i-1]){
+					throw new RuntimeException("Array ["+join(arr,",")+"] is not sorted desc!");
+				}
+			}
+			return;
+		}
+	}
+
+
+	/**
+	 * 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[] newArr = new int[oldArray.length+size];
+		for(int i=0;i<oldArray.length;i++){
+			newArr[i] = oldArray[i];
+		}
+		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 int[] fibonacci(int max){
+		if(max==1){
+			return new int[0];
+		}else if(max==2){
+			return new int[]{1,1};
+		}else{
+			int[] arr = new int[max];
+			arr[0]=1;
+			arr[1]=1;
+			int pos=2;
+			genFibonacci(arr,pos,max);
+
+			int[] result = removeZero(arr);
+			return result;
+		}
+	}
+	private void genFibonacci(int[] arr,int pos,int max){
+		int val = arr[pos-2]+arr[pos-1];
+		if(val<max){
+			arr[pos]=val;
+			pos++;
+			genFibonacci(arr,pos,max);
+		}else{
+			return;
+		}
+	}
+
+	/**
+	 * 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[] nonPrimeArr = new int[max];
+		int tmp;
+		//begin to calculate for nonPrime,start from 4 because 2 & 3 can not be calculated in this way
+		for(int i=2;i<max;i++){
+			for(int j=2;j<=i;j++){
+				tmp = i*j;
+				if(tmp<max){
+					//Mark as nonPrime numbers
+					nonPrimeArr[tmp]=1;
+				}else{
+					break;
+				}
+			}
+		}
+		int[] result = new int[max];
+		int pos = 0;
+		if(max>3){
+			result[pos]=2;
+			pos++;
+		}
+		if(max>4){
+			result[pos]=3;
+			pos++;
+		}
+		for(int i=4;i<nonPrimeArr.length;i++){
+			//for those value==0, mean indicated as Primes,index is the prime number
+			if(nonPrimeArr[i]==0){
+				result[pos]=i;
+				pos++;
+			}
+		}
+
+		result = removeZero(result);
+		return result;
+	}
+
+	/**
+	 * 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){
+		if(max<=1){
+			throw new RuntimeException("Invalid Arguement :max number="+max);
+		}else{
+			int[] result = new int[max];
+			int pos = 0;
+			for(int i=2;i<=max;i++){
+				int[] factors = getFactors(i);
+				int val =0;
+				//Sum of the factors
+				for(int j:factors){
+					val+=j;
+				}
+				//Check if the sum of factors equals to the number
+				if(val==i){
+					result[pos]=i;
+					pos++;
+				}
+			}
+			result = removeZero(result);
+			return result;
+		}
+	}
+
+	/**
+	 * Get the factor of a integer
+	 * @param num
+	 * @return factors of this number as int array 
+	 */
+	private int[] getFactors(int num){
+		int[] factors = new int[num];
+		int pos = 0;
+		for(int i=1;i<=num/2;i++){
+			if(num%i==0){
+				factors[pos]=i;
+				pos++;
+			}
+		}
+		return removeZero(factors);
+	}
+
+	/**
+	 * 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){
+		StringBuilder sb = new StringBuilder();
+		for(int i: array){
+			if(sb.length()>0){
+				sb.append(seperator);
+			}
+			sb.append(i);
+		}
+		return sb.toString();
+	}
+
+	private void printArray(String msg,int[] array){
+		System.out.print(msg);
+		for(int i=0;i<array.length;i++){
+			System.out.print(array[i]+",");
+		}
+		System.out.println();
+	}
+}