JAVA数据结构之递归

 

/*折半查找（二分查找）的递归和非递归算法*/public class BinarySearch<T extends Comparable<T>>{private T[] data;public BinarySearch(T[] data){this.data = data;}public int search(T key){int low;int high;int mid;if(data == null)return -1;low = 0;high = data.length - 1;while(low <= high){mid = (low + high) / 2;System.out.println("mid " + mid + "mid value:" + data[mid]);if(key.compareTo(data[mid]) < 0){high = mid - 1;}else if(key.compareTo(data[mid]) > 0){low = mid + 1;}else if(key.compareTo(data[mid]) == 0){return mid;}}return -1;}private int doSearchRecursively(int low,int high,T key){int mid;int result;if(low <= high){mid = (low + high) / 2;result = key.compareTo(data[mid]);System.out.println("mid " + mid + " mid value:" + data[mid]);if(result < 0){return doSearchRecursively(low,mid - 1,key);}else if(result > 0){return doSearchRecursively(mid+1,high,key);}else if(result == 0){return mid;}}return -1;}public int searchRecursively(T key){if(data == null) return -1;return doSearchRecursively(0,data.length - 1,key);}public static void main(String[] args){Integer []data = {1,4,5,8,15,33,48,77,96};//BinarySearch<Integer> binSearch = new BinarySearch<Integer>(data);//System.out.println("Key index:" + binSearch.searchRecursively(3));//System.out.println("Key index:" + binSearch.search(33));//String []dataStr = {"A","C","F","J","L","N","T"};//BinarySearch<String> binSearch = new BinarySearch<String>(dataStr);//System.out.println("Key index:"+binSearch.search("F"));}} 

 

 

public class Test1{public static void main(String []args){int t[] = {1,2,4,3};range(t,0);}public static void range(int []a,int start){if(start == a.length){for(int i =0;i<a.length;i++){System.out.print(a[i]);}System.out.println();return;}for(int i = start;i<a.length;i++){int temp = a[start];a[start] = a[i];a[i] = temp;range(a,start+1);a[i] = a[start];a[start] = temp;}}} 

 

 

public class Test2{public static void main(String args[]){int t[] = {1,2,4,3};range(t,0);}public static void range(int[] a,int start){if(start == a.length){for(int i=0;i<a.length;i++){System.out.print(a[i]);}System.out.println();return;}int dest[] = new int[a.length];System.arraycopy(a,0,dest,0,a.length);for(int i = start;i<a.length;i++){int temp = dest[start];dest[start] = dest[i];dest[i] = temp;range(dest,start + 1);}}} 

 

 

public class Test3{public static void main(String args[]){int t[] = {1,2,3,4};range(t,0);}public static void range(int[] a,int start){if(start == a.length){for(int i=0;i<a.length;i++){System.out.print(a[i]);}System.out.println();return;}for(int i = start;i<a.length;i++){int dest[] = new int[a.length];System.arraycopy(a,0,dest,0,a.length);int temp = dest[start];dest[start] = dest[i];dest[i] = temp;range(dest,start + 1);}}} 

 

 

public class ArraySh{int []theArray;int nElems;int count = 0;ArraySh(int max){theArray = new int[max];nElems = max;}public static void main(String[] args){int maxSize = 16;ArraySh arr;arr = new ArraySh(maxSize);for(int j=0;j<maxSize;j++){int n = (int)(java.lang.Math.random() * 99);arr.insert(n);}arr.display();arr.quickSort();arr.display();}public void insert(int i){theArray[count++] = i;}public void display(){for(int i : theArray){System.out.print(i+" ");}System.out.println();}public void quickSort(){recQuickSort(0,nElems - 1);}public void recQuickSort(int left,int right){if(right - left <= 0)return;else{long pivot = theArray[right];int partition = partitionIt(left,right,pivot);recQuickSort(left,partition-1);recQuickSort(partition+1,right);}}public int partitionIt(int left,int right,long pivot){int leftPtr = left - 1;int rightPtr = right;while(true){while(theArray[++leftPtr] < pivot);while(rightPtr > 0 && theArray[--rightPtr] > pivot);if(leftPtr >= rightPtr)break;elseswap(leftPtr,rightPtr);}swap(leftPtr,right);return leftPtr;}public void swap(int dex1,int dex2){int temp = theArray[dex1];theArray[dex1] = theArray[dex2];theArray[dex2] = temp;}} 

 

 

 

//package sort;import java.util.Date;import java.util.Random;/* * 插入排序 */public class InsertSort{public static void main(String args[]){int len = 20;Date date = new Date();Random random = new Random(date.getSeconds());int data[]=new int[len];for(int i = 0; i < len; i++){data[i]=(int)(random.nextFloat()*100+1);}show(data);insertSort(data,data.length);show(data);System.out.println(binarySearch(data,1,data.length,55));System.out.println(binarySearch2(data,55));insertSortDesc(data);show(data);System.out.println(binarySearch(data,1,data.length,55));System.out.println(binarySearch2(data,55));}/* * 插入排序核心 */private static void insertSortDesc(int[] data){int length = data.length;for(int i = 1; i < length; i++){int temp = data[i];int j = i-1;while(j >= 0 && data[j] < temp){data[j+1] = data[j];j--;}data[j+1] = temp;}}private static void insertSortAsc(int[] data){int length = data.length;for(int i = 1; i < length; i++){int temp = data[i];int j = i-1;while(j >= 0 && data[j] > temp){data[j+1] = data[j];j--;}data[j+1] = temp;}}private static void show(int[] data){System.out.println("========================");for(int i = 0; i < data.length; i++){System.out.print(data[i] + " ");}System.out.println();System.out.println("========================");}/* * 使用递归实现的插入排序算法 */private static void insertSort(int[] data,int n){if(n>1){insertSort(data,n-1);merge(data,n-1,n);}}private static void merge(int[] data,int end,int n){int temp=data[n-1];int i;for( i=end-1; i>=0; i--){if(data[i]>temp)data[i+1]=data[i];elsebreak;}data[i+1]=temp;}/* * 递归版的二分查找算法,只能是按照升序排列的数组 */private static int binarySearch(int[] data,int start,int end,int value){if(end>=start){int pos=(start+end)/2;if(value==data[pos-1])return pos;else if(value>data[pos-1])return binarySearch(data,pos+1,end,value);elsereturn binarySearch(data,start,pos-1,value);}return -1;}/* * 迭代版二分查找算法，只能查找按照升序排列的数组 */private static int binarySearch2(int[] data,int value){int start = 0 ;int end = data.length-1;int mid;while(end>=start){mid=(end+start)/2;if(value>data[mid])start=mid+1;else if(value<data[mid])end=mid-1;elsereturn mid+1;}return -1;}}