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RotateList61.java
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RotateList61.java
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package linkedList;
public class RotateList61 {
public ListNode rotateRight(ListNode head, int k) {
int len = 0;
ListNode node = head;
while (node != null) {
len++;
node = node.next;
}
k = k % len;
if (k == 0) {
return head;
}
ListNode dummy = new ListNode(-1);
dummy.next = head;
ListNode slow = dummy;
ListNode fast = dummy;
for (int i = 0; i <= k; i++) {
fast = fast.next;
}
while (fast != null) {
fast = fast.next;
slow = slow.next;
}
ListNode newHead = slow.next;
slow.next = null;
node = newHead;
while (node.next != null) {
node = node.next;
}
node.next = dummy.next;
dummy.next = newHead;
return dummy.next;
}
/**
* 代码优化
*
* @param head
* @param k
* @return
*/
public ListNode rotateRightV2(ListNode head, int k) {
if(head==null || head.next == null) return head;
ListNode dummy = new ListNode(-1);
dummy.next = head;
int len = 0;
ListNode fast = dummy;
ListNode slow = dummy;
for(;fast.next!=null;len++){
fast = fast.next;
}
for(int i=len-k%len;i>0;i--){
slow = slow.next;
}
fast.next = dummy.next;
dummy.next = slow.next;
slow.next = null;
return dummy.next;
}
public static void main(String[] args) {
ListNode node1 = new ListNode(1);
ListNode node2 = new ListNode(2);
ListNode node3 = new ListNode(3);
ListNode node4 = new ListNode(4);
ListNode node5 = new ListNode(5);
ListNode node6 = new ListNode(6);
node1.next = node2;
node2.next = node3;
node3.next = node4;
node4.next = node5;
// node5.next = node6;
ListNode head = new RotateList61().rotateRightV2(node1, 2);
while (head != null) {
System.out.print(head.val + "\t");
head = head.next;
}
}
}