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92.java
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92.java
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__________________________________________________________________________________________________
sample 0 ms submission
/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
*/
public class Solution {
//Time: O(n), Space: O(1)
public ListNode reverseBetween(ListNode head, int m, int n) {
if (head == null || head.next == null || m == n) {
return head;
}
ListNode dummy = new ListNode(-1);
dummy.next = head;
ListNode prev = dummy;
for (int i = 1; i < m; i++) {
prev = prev.next;
}
prev.next = reverse(prev.next, n - m + 1);
return dummy.next;
}
private ListNode reverse(ListNode head, int k) {
ListNode tail = head;
ListNode prev = null;
for (int i = 0; i < k; i++) {
ListNode temp = head.next;
head.next = prev;
prev = head;
head = temp;
}
tail.next = head;
return prev;
}
}
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sample 34152 kb submission
/**
* Definition for singly-linked list.
* public class ListNode {
* int val;
* ListNode next;
* ListNode(int x) { val = x; }
* }
*/
class Solution {
public ListNode reverseBetween(ListNode head, int m, int n) {
ListNode dummy = new ListNode(0);
dummy.next = head;
ListNode curr = dummy,
tail = dummy;
int i;
for (i = 0; i < m - 1; ++i) {
curr = curr.next;
}
for (i = 0; i < n; ++i) {
tail = tail.next;
}
while (curr.next != tail) {
ListNode tmp = curr.next;
curr.next = tmp.next;
tmp.next = tail.next;
tail.next = tmp;
}
return dummy.next;
}
}
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