排序算法

选择排序

public class Selection {
    
    public void Selection(){
        int a[]={49,38,65,97,76,13,27,49,78,34,12,64,5,4,62,99,98,54,56,17,18,23,34,15,35,25,53,51}; 
        for(int i=0;i<a.length;i++){
            for(int j=i;j<a.length;j++){
                if(a[i]>a[j]){
                    int temp;
                    temp=a[i];
                    a[i]=a[j];
                    a[j]=temp;
                }
                
            }
        }
        for(int i=0;i<a.length;i++){
            System.out.print(a[i]+" ");
        }

    }21 }

插入排序

public class InsertSort {
    
        public static void insertSort(int[] a) {  
            for(int i=1;i<a.length;i++){
                for(int j=i;j>0 && a[j]<a[j-1];j--){
                        int temp=a[j];
                        a[j]=a[j-1];
                        a[j-1]=temp;
                }
            }
        }  
      
        public static void main(String[] args) {  
            int[] array = {49,38,65,97,76,13,27,49,78,34,12,64,5,4,62,99,98,54,56,17,18,23,34,15,35,25,53,51,2};  
             SortUtil util = new SortUtil();
             util.print(array);
             insertSort(array);  
             util.print(array);
        }  
    }

希尔排序

package sort;

public class ShellSort {
    public static void Shell(int[] a){
        int n = a.length;
        int h = 1;
        while(h<n/3) h=3*h+1;
        while(h>=1){
            for(int i=h;i<n;i++){
                for(int j=i;j>=h && a[j]<a[j-h];j-=h){
                    int temp=a[j];
                    a[j]=a[j-h];
                    a[j-h]=temp;
                }
            }
            h=h/3;
        }
    }
    public static void main(String arg[]){
        int[] array={49,38,65,97,76,13,27,49,78,34,12,64,5,4,62,99,98,54,56,17,18,23,34,15,35,25,53,51,1,};
        SortUtil sort =new SortUtil();
        sort.print(array);
        ShellSort.Shell(array);
        sort.print(array);
    } 
}

 

归并排序

package sort;

public class Merge {
    private static int[] aux;
    public static void sort(int[] a){
        aux = new int[a.length];
        sort(a, 0, a.length-1); 
    }
    private static void sort(int[] a,int lo,int hi){
        if(lo>=hi) return;
        int mid=lo+(hi-lo)/2;
        sort( a, lo, mid);
        sort( a, mid+1, hi);
        Merge(a,lo,mid,hi);
    }
    private static void Merge(int[] a,int lo,int mid,int hi){
        int i=lo,j=mid+1;
        for(int k=lo;k<=hi;k++)
            aux[k]=a[k];
        
        for(int k=lo;k<=hi;k++){
            if(i>mid) a[k]=aux[j++];
            else if(j>hi)  a[k]=aux[i++];
            else if(aux[i]<aux[j]) a[k]=aux[i++];
            else  a[k]=aux[j++];
        }
    }
    public static void main(String[] args) {  
         int[] array = {49,38,65,97,76,13,27,49,78,34,12,64,5,4,62,99,98,54,56,17,18,23,34,15,35,25,53,51,2};  
         SortUtil util = new SortUtil();
         util.print(array);
         sort(array);  
         util.print(array);
    }
}

 快速排序

public class Quick {
    public static void sort(int[ ] a){
        //StdRandom.shuffle
        sort(a,0,a.length -1);
    }

    private static void sort(int[] a, int lo, int hi) {
        if(hi<=lo) return;
        int j = partition(a,lo,hi);
        sort(a,lo,j-1);
        sort(a,j+1,hi);
    }

    private static int partition(int[] a, int lo, int hi) {
        int v = a[lo];
        int i=lo,j=hi+1;
        while(true){
            while(v>a[++i]) if(i==hi) break;
            while(v<a[--j]) if(j==lo) break;
            if(i>=j) break;
            int temp=a[j];
            a[j]=a[i];
            a[i]=temp;
        }
        int temp = a[j];
        a[j]=a[lo];
        a[lo]=temp;
        return j;
    }
    
    public static void main(String[] args) {  
        int[] array = {49,38,65,97,76,13,27,49,78,34,12,64,5,4,62,99,98,54,56,17,18,23,34,15,35,25,53,51,2};  
         SortUtil util = new SortUtil();
         util.print(array);
         sort(array);  
         util.print(array);
    }  
    
}

冒泡排序

public class BubbleSort{
    public static void Bubble(){
        int score[] = {67, 69, 75, 87, 89, 90, 99, 100};
        for (int i = 0; i < score.length -1; i++){    //最多做n-1趟排序
            for(int j = 0 ;j < score.length - i - 1; j++){    //对当前无序区间score[0......length-i-1]进行排序
                                                              //(j的范围很关键，这个范围是在逐步缩小的)
                if(score[j] > score[j + 1]){        //把小的值交换到后面
                    int temp = score[j];
                    score[j] = score[j + 1];
                    score[j + 1] = temp;
                }
            }            
            System.out.print("第" + (i + 1) + "次排序结果：");
            for(int a = 0; a < score.length; a++){
                System.out.print(score[a] + "\t");
            }
            System.out.println("");
        }
            System.out.print("最终排序结果：");
            for(int a = 0; a < score.length; a++){
                System.out.print(score[a] + "\t");
       }
    }
    public static void main(String[] args){
        BubbleSort.Bubble();
    }
}