按照左右區間的方式重新組合單鏈表
阿新 • • 發佈：2019-01-07
class Solution {
private static ListNode split(ListNode head) {
if (head == null || head.next == null) {
return head;
}
ListNode pre = null;
ListNode slow = head;
ListNode fast = head.next.next;
int num = 2;
while (fast != null) {
pre = slow;
slow = slow.next;
if (fast.next == null) {
num += 1;
break;
}
num += 2;
fast = fast.next.next;
}
if (num % 2 == 0) {
ListNode result = slow.next;
slow.next = null;
return result;
}
pre.next = null;
return slow;
}
private static ListNode merge(ListNode l1, ListNode l2) {
if (l1 == null) {
return l2;
}
ListNode head = new ListNode(-1);
ListNode p = head;
while (l1 != null) {
ListNode l1Next = l1.next;
ListNode l2Next = l2.next;
p.next = l1;
p = p.next;
p.next = l2;
p = p.next;
l1 = l1Next;
l2 = l2Next;
}
p.next = l2;
return head.next;
}
private static ListNode function(ListNode head) {
if (head == null || head.next == null || head.next.next == null) {
return null;
}
return merge(head, split(head));
}
private static void print(ListNode head, Integer limit) {
if (limit == null) {
limit = Integer.MAX_VALUE;
}
while (head != null && limit -- > 0) {
System.out.println(head.val);
head = head.next;
}
}
public static void main(String[] args) {
ListNode n1 = new ListNode(1);
ListNode n2 = new ListNode(2);
ListNode n3 = new ListNode(3);
ListNode n4 = new ListNode(4);
ListNode n5 = new ListNode(5);
ListNode n6 = new ListNode(6);
ListNode n7 = new ListNode(7);
ListNode n8 = new ListNode(8);
n1.next = n2;
n2.next = n3;
n3.next = n4;
n4.next = n5;
n5.next = n6;
// n6.next = n7;
// n7.next = n8;
ListNode head = function(n1);
print(head, 100);
}
}
class ListNode {
int val;
ListNode next;
ListNode(int x) { val = x; }
}