leetcode/src/problems/LeetCode92.java at master · codinglin/leetcode · GitHub

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package problems;

public class LeetCode92 {
    public ListNode reverseBetween(ListNode head, int left, int right) {
        ListNode dummyNode = new ListNode(-1);
        dummyNode.next = head;
        ListNode pre = dummyNode;
        for (int i = 0; i < left - 1; i++) {
            pre = pre.next;
        }
        ListNode cur = pre.next;
        ListNode next;
        for (int i = 0; i < right - left; i++) {
            next = cur.next;
            cur.next = next.next;
            next.next = pre.next;
            pre.next = next;
        }
        return dummyNode.next;
    }
}

class LeetCode92_1 {
    public ListNode reverseBetween(ListNode head, int left, int right) {
        ListNode dummyNode = new ListNode(-1);
        dummyNode.next = head;
        ListNode pre = dummyNode;
        for (int i = 0; i < left - 1; i++) {
            pre = pre.next;
        }
        ListNode cur = pre.next;
        ListNode next;
        for (int i = 0; i < right - left; i++) {
            next = cur.next;
            cur.next = next.next;
            next.next = pre.next;
            pre.next = next;
        }
        return dummyNode.next;
    }

//    private ListNode reverse(ListNode head) {
//        ListNode cur = null;
//        while (head.next != null) {
//            ListNode temp = head;
//            head = head.next;
//            temp.next = cur;
//            cur = temp;
//        }
//        return cur;
//    }
}