基于链表的快速排序及归并排序

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归并排序

package 算法和数据结构;/*** Filename : LinkedList_MergeSort.java* Author : zhihao_tian@126.com* Creation time : 下午5:47:02 - 2017年3月26日* Description :*/class ListNode {    int val;    ListNode next;    ListNode(int x){        val = x;        next = null;    }}public class LinkedList_MergeSort{    public ListNode sortList(ListNode head){        if(head==null||head.next==null){            return head;        }        ListNode mid=findMid(head);        ListNode right=mid.next;        mid.next=null;        return merge(sortList(head),sortList(right));    }    private ListNode merge(ListNode head1,ListNode head2){        ListNode dummy=new ListNode(0);        ListNode cur=dummy;        while(head1!=null&&head2!=null){            if(head1.val<=head2.val){                cur.next=head1;                head1=head1.next;            }else{                cur.next=head2;                head2=head2.next;            }            cur=cur.next;        }        if(head1!=null){            cur.next=head1;        }else if(head2!=null){            cur.next=head2;        }        return dummy.next;    }    private ListNode findMid(ListNode head){        if(head==null){            return head;        }        ListNode slow=head;        ListNode fast=head;        while(fast.next!=null&&fast.next.next!=null){            fast=fast.next.next;            slow=slow.next;        }        return slow;    }}

快速排序

package 算法和数据结构;/*** Filename : LinkedList_QuickSort.java* Author : zhihao_tian@126.com* Creation time : 下午5:50:18 - 2017年3月26日* Description :*/public class LinkedList_QuickSort{    public ListNode sortList(ListNode head){        return quickSort(head,null);    }    private ListNode quickSort(ListNode head,ListNode end){        if(head!=end){            ListNode cur=partion(head,end);            quickSort(head,cur);            quickSort(cur.next,end);        }        return head;    }    private ListNode partion(ListNode head,ListNode end){        int key=head.val;        ListNode p=head;        ListNode q=head.next;        while(q!=end){            if(q.val<key){                p=p.next;                swap(p,q);            }            q=q.next;        }        swap(head,p);        return p;    }    private void swap(ListNode p,ListNode q){        int temp=p.val;        p.val=q.val;        q.val=temp;    }}

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