Java基础算法--排序

一、插入排序

　　数组：　　

void insertionSort(int[] a){
    int j;
    for(int p = 1;p<a.length;p++){
        int tmp = a[p];
        for(j=p;j>0;j--){
            if(tmp<a[j-1]){
                a[j] = a[j-1];
            }else{
                a[i] = tmp;
            }
        }    
    }
}

　　若是Java泛型掌握的好，可以这样书写

void insertionSort(AnyType[] a){
    int j;
    for(int p = 1;p < a.length;p++){
        AnyType tmp = a[p];
        for(j=p;j>0&&tmp.compareTo(a[j-1])<0;j--)            
            a[j] = a[j-1];    
        a[i] = tmp;    
    }    
}

　　链表：

public class Solution {
    public ListNode insertionSortList(ListNode head) {
        ListNode dummy = new ListNode(-1);
        dummy.next = head;
        head = dummy;
        ListNode p = dummy.next;
        ListNode s;
        
        while(p!=null){
            if(p.next==null)  break;
            while(head!=p&&p.next.val>head.next.val){
                head=head.next;
            }
            if(head==p)
                p=p.next;
            else{
                s = p.next;
                p.next = p.next.next;
                s.next = null;
                
                ListNode tmp = head.next;
                head.next = s;
                s.next = tmp;
            }
            head=dummy;
        }
        return dummy.next;
    }
}

 另一种于九章算法上的做法：

public class Solution {
    public ListNode insertionSortList(ListNode head) {
        ListNode dummy = new ListNode(0);

        while (head != null) {
            ListNode node = dummy;
            while (node.next != null && node.next.val < head.val) {
                node = node.next;
            }
            ListNode temp = head.next;
            head.next = node.next;
            node.next = head;
            head = temp;
        }

        return dummy.next;
    }
}