05 August 2008
给一个k，左右两端的距离ends为k的两个nodes进行swap
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
Put slow at head, and put fast k-1 nodes after slow.
first = fast.
If fast isn't already at the last node, move slow and fast one node further until fast.next == null
second = slow
Swap the values of first and second ```java class Solution {
public ListNode swapNodes(ListNode head, int k) {
ListNode fast = head;
ListNode slow = head;
ListNode first = head, second = head;
// Put fast (k-1) nodes after slow
for(int i = 0; i < k - 1; ++i)
fast = fast.next;
// Save the node for swapping
first = fast;
// Move until the end of the list
while(fast.next != null) {
slow = slow.next;
fast = fast.next;
}
// Save the second node for swapping
// Note that the pointer second isn't necessary: we could use slow for swapping as well
// However, having second improves readability
second = slow;
// Swap values
int temp = first.val;
first.val = second.val;
second.val = temp;
return head;
} } ```