Java實現-翻轉鏈表2

翻轉鏈表中第m個節點到第n個節點的部分

 注意事項

m，n滿足1 ≤ m ≤ n ≤ 鏈表長度

您在真實的面試中是否遇到過這個題？ 

Yes

樣例

給出鏈表1->2->3->4->5->null， m = 2 和n = 4，返回1->4->3->2->5->nul

/**
 * Definition for ListNode
 * public class ListNode {
 *     int val;
 *     ListNode next;
 *     ListNode(int x) {
 *         val = x;
 *         next = null;
 *     }
 * }
 */
public class Solution {
    /**
     * @param ListNode head is the head of the linked list 
     * @oaram m and n
     * @return: The head of the reversed ListNode
     */
    public ListNode reverseBetween(ListNode head, int m , int n) {
        // write your code
        if(m==n){
			return head;
		}
		ListNode dummy=new ListNode(-1);
		dummy.next=head;
		ListNode m_Pre=dummy;
		while(m>1){
			m_Pre=m_Pre.next;
			m--;
			n--;
		}
		Stack<ListNode> stack=new Stack<ListNode>();
		while(n>0){
			ListNode node=m_Pre.next;
			m_Pre.next=node.next;
			node.next=null;
			stack.push(node);
			n--;
		}
		while(!stack.isEmpty()){
			ListNode node=stack.pop();
			node.next=m_Pre.next;
			m_Pre.next=node;
			m_Pre=m_Pre.next;
		}
		return dummy.next;
    }
}