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ReverseNodesInKGroup.java
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ReverseNodesInKGroup.java
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/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) {
* val = x;
* next = null;
* }
* }
*/
public class Solution {
public ListNode reverse (ListNode p, int k) {
int j = 0;
ListNode new_tail = p.next;
while (j < k - 1) {
ListNode tmp = new_tail.next;
new_tail.next = new_tail.next.next;
tmp.next = p.next;
p.next = tmp;
j += 1;
}
return new_tail;
}
public ListNode reverseKGroup(ListNode head, int k) {
ListNode dummy = new ListNode(0);
dummy.next = head;
Boolean reverse = true;
ListNode p = dummy;
while (true) {
int i = 0;
ListNode tmp = p;
while (i < k) {
if (tmp.next == null) {
reverse = false;
break;
}
tmp = tmp.next;
i += 1;
}
if (reverse == false) {
break;
}
p = this.reverse(p, k);
}
return dummy.next;
}
}