链表_leetcode61

# Definition for singly-linked list.
class ListNode(object):
    def __init__(self, x):
        self.val = x
        self.next = None

class Solution(object):
    def rotateRight(self, head, k):
        """
        :type head: ListNode
        :type k: int
        :rtype: ListNode
        """


        if not head or not head.next:
            return head

        dummyHead = ListNode(0)
        dummyHead.next = head

        pre = dummyHead

        tail = head
        sum = 1

        while tail.next:
            pre = pre.next
            tail = tail.next
            sum += 1



        count = k % sum

        while count:

            pre.next = tail.next
            tail.next =  dummyHead.next
            dummyHead.next = tail

            pre , tail = self.getTail(dummyHead.next)


        return dummyHead.next


    def getTail(self,head):
        pre = head
        tail = head.next

        while tail.next:
            pre = tail
            tail = tail.next

        return pre ,tail


    def creatList(self,l):
        dummyHead = ListNode(0)

        pre = dummyHead

        for i in  l:
            pre.next = ListNode(i)
            pre = pre.next

        return dummyHead.next


    def printList(self,head):
        cur = head

        while cur:
            print cur.val
            cur = cur.next



l1 = [1,2,3,4,5,6]

k = 2

s = Solution()# Definition for singly-linked list.
class ListNode(object):
    def __init__(self, x):
        self.val = x
        self.next = None

class Solution(object):
    def rotateRight(self, head, k):
        """
        :type head: ListNode
        :type k: int
        :rtype: ListNode
        """


        if not head or not head.next:
            return head

        dummyHead = ListNode(0)
        dummyHead.next = head

        pre = dummyHead

        tail = head
        sum = 1

        while tail.next:
            pre = pre.next
            tail = tail.next
            sum += 1



        count = k % sum

        # pre.next = tail.next
        # tail.next =  dummyHead.next
        # dummyHead.next = tail
        #
        # self.printList(dummyHead.next)
        #
        # pre, tail = self.getTail(dummyHead.next)
        #
        # # print pre.val
        # # print tail.val
        #
        # pre.next = tail.next
        # tail.next = dummyHead.next
        # dummyHead.next = tail
        #
        # self.printList(dummyHead.next)


        while count > 0:

            pre.next = tail.next
            tail.next =  dummyHead.next
            dummyHead.next = tail

            pre , tail = self.getTail(dummyHead.next)

            count -= 1


        return dummyHead.next


    def getTail(self,head):
        pre = head
        tail = head.next

        while tail.next:
            pre = tail
            tail = tail.next

        return pre ,tail


    def creatList(self,l):
        dummyHead = ListNode(0)

        pre = dummyHead

        for i in  l:
            pre.next = ListNode(i)
            pre = pre.next

        return dummyHead.next


    def printList(self,head):
        cur = head

        while cur:
            print cur.val
            cur = cur.next



l1 = [1,2,3,4,5]

k = 2

s = Solution()

head = s.creatList(l1)

s.printList(head)

s.rotateRight(head,2)