java排序算法

2024年1月15日 135次阅读

插入排序：

package org.rut.util.algorithm.support;

import org.rut.util.algorithm.SortUtil;

public class InsertSort implements SortUtil.Sort{

/* (non-Javadoc)
 * @see org.rut.util.algorithm.SortUtil.Sort#sort(int[])
 */
public void sort(int[] data) {
    int temp;
    for(int i=1;i<data.length;i++){
        for(int j=i;(j>0)&&(data[j]<data[j-1]);j--){
            SortUtil.swap(data,j,j-1);
        }
    }        
}

}

冒泡排序：

package org.rut.util.algorithm.support;

import org.rut.util.algorithm.SortUtil;

public class BubbleSort implements SortUtil.Sort{

/* (non-Javadoc)
 * @see org.rut.util.algorithm.SortUtil.Sort#sort(int[])
 */
public void sort(int[] data) {
    int temp;
    for(int i=0;i<data.length;i++){
        for(int j=data.length-1;j>i;j--){
            if(data[j]<data[j-1]){
                SortUtil.swap(data,j,j-1);
            }
        }
    }
}

}

选择排序：

package org.rut.util.algorithm.support;

import org.rut.util.algorithm.SortUtil;

public class SelectionSort implements SortUtil.Sort {

/*
 * (non-Javadoc)
 * 
 * @see org.rut.util.algorithm.SortUtil.Sort#sort(int[])
 */
public void sort(int[] data) {
    int temp;
    for (int i = 0; i < data.length; i++) {
        int lowIndex = i;
        for (int j = data.length - 1; j > i; j--) {
            if (data[j] < data[lowIndex]) {
                lowIndex = j;
            }
        }
        SortUtil.swap(data,i,lowIndex);
    }
}

}

Shell排序：

package org.rut.util.algorithm.support;

import org.rut.util.algorithm.SortUtil;

public class ShellSort implements SortUtil.Sort{

/* (non-Javadoc)
 * @see org.rut.util.algorithm.SortUtil.Sort#sort(int[])
 */
public void sort(int[] data) {
    for(int i=data.length/2;i>2;i/=2){
        for(int j=0;j<i;j++){
            insertSort(data,j,i);
        }
    }
    insertSort(data,0,1);
}

/**
 * @param data
 * @param j
 * @param i
 */
private void insertSort(int[] data, int start, int inc) {
    int temp;
    for(int i=start+inc;i<data.length;i+=inc){
        for(int j=i;(j>=inc)&&(data[j]<data[j-inc]);j-=inc){
            SortUtil.swap(data,j,j-inc);
        }
    }
}

}

快速排序：

package org.rut.util.algorithm.support;

import org.rut.util.algorithm.SortUtil;

public class QuickSort implements SortUtil.Sort{

/* (non-Javadoc)
 * @see org.rut.util.algorithm.SortUtil.Sort#sort(int[])
 */
public void sort(int[] data) {
    quickSort(data,0,data.length-1);        
}
private void quickSort(int[] data,int i,int j){
    int pivotIndex=(i+j)/2;
    //swap
    SortUtil.swap(data,pivotIndex,j);

    int k=partition(data,i-1,j,data[j]);
    SortUtil.swap(data,k,j);
    if((k-i)>1) quickSort(data,i,k-1);
    if((j-k)>1) quickSort(data,k+1,j);

}
/**
 * @param data
 * @param i
 * @param j
 * @return
 */
private int partition(int[] data, int l, int r,int pivot) {
    do{
       while(data[++l]<pivot);
       while((r!=0)&&data[--r]>pivot);
       SortUtil.swap(data,l,r);
    }
    while(l<r);
    SortUtil.swap(data,l,r);        
    return l;
}

}

改进后的快速排序：

package org.rut.util.algorithm.support;

import org.rut.util.algorithm.SortUtil;

public class ImprovedQuickSort implements SortUtil.Sort {

private static int MAX_STACK_SIZE=4096;
private static int THRESHOLD=10;
/* (non-Javadoc)
 * @see org.rut.util.algorithm.SortUtil.Sort#sort(int[])
 */
public void sort(int[] data) {
    int[] stack=new int[MAX_STACK_SIZE];

    int top=-1;
    int pivot;
    int pivotIndex,l,r;

    stack[++top]=0;
    stack[++top]=data.length-1;

    while(top>0){
        int j=stack[top--];
        int i=stack[top--];

        pivotIndex=(i+j)/2;
        pivot=data[pivotIndex];

        SortUtil.swap(data,pivotIndex,j);

        //partition
        l=i-1;
        r=j;
        do{
            while(data[++l]<pivot);
            while((r!=0)&&(data[--r]>pivot));
            SortUtil.swap(data,l,r);
        }
        while(l<r);
        SortUtil.swap(data,l,r);
        SortUtil.swap(data,l,j);

        if((l-i)>THRESHOLD){
            stack[++top]=i;
            stack[++top]=l-1;
        }
        if((j-l)>THRESHOLD){
            stack[++top]=l+1;
            stack[++top]=j;
        }

    }
    //new InsertSort().sort(data);
    insertSort(data);
}
/**
 * @param data
 */
private void insertSort(int[] data) {
    int temp;
    for(int i=1;i<data.length;i++){
        for(int j=i;(j>0)&&(data[j]<data[j-1]);j--){
            SortUtil.swap(data,j,j-1);
        }
    }       
}

}

归并排序：

package org.rut.util.algorithm.support;

import org.rut.util.algorithm.SortUtil;

public class MergeSort implements SortUtil.Sort{

/* (non-Javadoc)
 * @see org.rut.util.algorithm.SortUtil.Sort#sort(int[])
 */
public void sort(int[] data) {
    int[] temp=new int[data.length];
    mergeSort(data,temp,0,data.length-1);
}

private void mergeSort(int[] data,int[] temp,int l,int r){
    int mid=(l+r)/2;
    if(l==r) return ;
    mergeSort(data,temp,l,mid);
    mergeSort(data,temp,mid+1,r);
    for(int i=l;i<=r;i++){
        temp<i>=data<i>;
    }
    int i1=l;
    int i2=mid+1;
    for(int cur=l;cur<=r;cur++){
        if(i1==mid+1)
            data[cur]=temp[i2++];
        else if(i2>r)
            data[cur]=temp[i1++];
        else if(temp[i1]<temp[i2])
            data[cur]=temp[i1++];
        else
            data[cur]=temp[i2++];            
    }
}

}

改进后的归并排序:

package org.rut.util.algorithm.support;

import org.rut.util.algorithm.SortUtil;

public class ImprovedMergeSort implements SortUtil.Sort {

private static final int THRESHOLD = 10;

/*
 * (non-Javadoc)
 * 
 * @see org.rut.util.algorithm.SortUtil.Sort#sort(int[])
 */
public void sort(int[] data) {
    int[] temp=new int[data.length];
    mergeSort(data,temp,0,data.length-1);
}

private void mergeSort(int[] data, int[] temp, int l, int r) {
    int i, j, k;
    int mid = (l + r) / 2;
    if (l == r)
        return;
    if ((mid - l) >= THRESHOLD)
        mergeSort(data, temp, l, mid);
    else
        insertSort(data, l, mid - l + 1);
    if ((r - mid) > THRESHOLD)
        mergeSort(data, temp, mid + 1, r);
    else
        insertSort(data, mid + 1, r - mid);

    for (i = l; i <= mid; i++) {
        temp<i> = data<i>;
    }
    for (j = 1; j <= r - mid; j++) {
        temp[r - j + 1] = data[j + mid];
    }
    int a = temp[l];
    int b = temp[r];
    for (i = l, j = r, k = l; k <= r; k++) {
        if (a < b) {
            data[k] = temp[i++];
            a = temp<i>;
        } else {
            data[k] = temp[j--];
            b = temp[j];
        }
    }
}


private void insertSort(int[] data, int start, int len) {
    for(int i=start+1;i<start+len;i++){
        for(int j=i;(j>start) && data[j]<data[j-1];j--){
            SortUtil.swap(data,j,j-1);
        }
    }
}

}

堆排序：

package org.rut.util.algorithm.support;

import org.rut.util.algorithm.SortUtil;

public class HeapSort implements SortUtil.Sort{

/* (non-Javadoc)
 * @see org.rut.util.algorithm.SortUtil.Sort#sort(int[])
 */
public void sort(int[] data) {
    MaxHeap h=new MaxHeap();
    h.init(data);
    for(int i=0;i<data.length;i++)
        h.remove();
    System.arraycopy(h.queue,1,data,0,data.length);
}

 private static class MaxHeap{         

    void init(int[] data){
        this.queue=new int[data.length+1];
        for(int i=0;i<data.length;i++){
            queue[++size]=data<i>;
            fixUp(size);
        }
    }

    private int size=0;

    private int[] queue;

    public int get() {
        return queue[1];
    }

    public void remove() {
        SortUtil.swap(queue,1,size--);
        fixDown(1);
    }
    //fixdown
    private void fixDown(int k) {
        int j;
        while ((j = k << 1) <= size) {
            if (j < size && queue[j]<queue[j+1])
                j++; 
            if (queue[k]>queue[j]) //不用交换
                break;
            SortUtil.swap(queue,j,k);
            k = j;
        }
    }
    private void fixUp(int k) {
        while (k > 1) {
            int j = k >> 1;
            if (queue[j]>queue[k])
                break;
            SortUtil.swap(queue,j,k);
            k = j;
        }
    }

}

}

SortUtil：

package org.rut.util.algorithm;

import org.rut.util.algorithm.support.BubbleSort;
import org.rut.util.algorithm.support.HeapSort;
import org.rut.util.algorithm.support.ImprovedMergeSort;
import org.rut.util.algorithm.support.ImprovedQuickSort;
import org.rut.util.algorithm.support.InsertSort;
import org.rut.util.algorithm.support.MergeSort;
import org.rut.util.algorithm.support.QuickSort;
import org.rut.util.algorithm.support.SelectionSort;
import org.rut.util.algorithm.support.ShellSort;

public class SortUtil {
public final static int INSERT = 1;
public final static int BUBBLE = 2;
public final static int SELECTION = 3;
public final static int SHELL = 4;
public final static int QUICK = 5;
public final static int IMPROVED_QUICK = 6;
public final static int MERGE = 7;
public final static int IMPROVED_MERGE = 8;
public final static int HEAP = 9;

public static void sort(int[] data) {
    sort(data, IMPROVED_QUICK);
}
private static String[] name={
        "insert", "bubble", "selection", "shell", "quick", "improved_quick", "merge", "improved_merge", "heap"
};

private static Sort[] impl=new Sort[]{
        new InsertSort(),
        new BubbleSort(),
        new SelectionSort(),
        new ShellSort(),
        new QuickSort(),
        new ImprovedQuickSort(),
        new MergeSort(),
        new ImprovedMergeSort(),
        new HeapSort()
};

public static String toString(int algorithm){
    return name[algorithm-1];
}

public static void sort(int[] data, int algorithm) {
    impl[algorithm-1].sort(data);
}

public static interface Sort {
    public void sort(int[] data);
}

public static void swap(int[] data, int i, int j) {
    int temp = data<i>;
    data<i> = data[j];
    data[j] = temp;
}

}

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