第六天算法设计

快速排序
需求：
排序前：{6,1,2,7,9,3,4,6,8}
排序后：{1,2,3,4,5,6,7,8,9}
算法设计：
Quic类：
package suanfa;

public class Quick {
private static boolean less(Comparable v,Comparable w){
return v.compareTo(w)<0;
}

private static void exch(Comparable[] a,int i,int j){
    Comparable t = a[i];
    a[i] =a[j];
    a[j] =t;
}

public static void sort(Comparable[] a){
    int lo = 0;
    int hi = a.length-1;
    sort(a,lo,hi);
}

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

}

public static int partition(Comparable[] a,int lo,int hi){
    Comparable key =a[lo];
    int left = lo;
    int right = hi+1;
    while (true){
        while (less(key,a[--right])){
            if(right==lo){
                break;
            }
        }
        while (less(a[++left],key)){
            if(left==hi){
                break;
            }
        }
        if(left>=right){
            break;
        }else {
            exch(a, left,right);
        }
    }
    exch(a,left,right);
    return right;

}

}

QuickTest类：
package suanfa;

import java.util.Arrays;

public class QuickTest {
public static void main(String[] args) {
Integer[] a={6,1,2,7,9,3,4,6,8};
Quick.sort(a);
System.out.println(Arrays.toString(a));
}

}
录制: untitled2 – Quick.java
录制文件：https://meeting.tencent.com/crm/KW4PbmpV58