golang刷leetcode 链表(3)反转链表

输入: 1->2->3->4->5->NULL, m = 2, n = 4
输出: 1->4->3->2->5->NULL

/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */
func reverseBetween(head *ListNode, m int, n int) *ListNode {
    if head==nil || head.Next==nil{
        return head
    }
    he:=&ListNode{}
    he.Next=head
    cur:=he
    for i:=0;i<m-1;i++{
        cur=cur.Next
    }
    h:=cur.Next
    t:=h.Next
    
    var tail *ListNode
    for j:=0;j<n-m;j++{
        temp:=t.Next
        t.Next=h
        if tail==nil{
            tail=h
        }
        h=t
        t=temp
    }
 cur.Next=h
    if tail!=nil{
 tail.Next=t
    }
    return he.Next
}

输入: head = 1->4->3->2->5->2, x = 3
输出: 1->2->2->4->3->5

/**
 * Definition for singly-linked list.
 * type ListNode struct {
 *     Val int
 *     Next *ListNode
 * }
 */
func partition(head *ListNode, x int) *ListNode { 
    if head==nil{
        return nil
    }
    var h1,t1,h2,t2 *ListNode
    for head!=nil {
        if head.Val<x{
           if h1==nil{
              h1=head
              t1=head
           }else{
               t1.Next=head
               t1=t1.Next
           } 
        }else{
             if h2==nil{
              h2=head
               t2=head
           }else{
               t2.Next=head
               t2=t2.Next
           } 
        }
       head=head.Next      
    }
    if t1!=nil{
         t1.Next=h2
    }else{
        return h2
    }
    
    if t2!=nil{
    t2.Next=nil
    }
    return h1
}