Leetcode Reverse Linked List II

题意：使得链表中的某一段倒序。

思路：简单模拟。

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* reverseBetween(ListNode* head, int m, int n) {
        if(head == NULL) return head;
        
        ListNode* myhead = new ListNode(0);
        myhead->next = head;
        
        ListNode* next = myhead;
        ListNode* s = myhead;
        ListNode* e = myhead;
        ListNode* s1 = myhead;
        int mym = m - 1;
        int myn = n;
        while(mym --) {
            s = s->next;
        }
        while(m --) {
            s1 = s1->next;
        }
        
        while(myn --) {
            e = e ->next;
        }
        ListNode* temp = e->next;
        
        reverseList(s1, e);
        s->next = e;
        s1->next = temp;//cout << "here";
        
        return myhead->next;
        
    }
    
    void reverseList(ListNode* s, ListNode* e) {
        stack<ListNode*> mys;
        while(s != e) {
            mys.push(s);
            s = s->next;
        }
        
        while(!mys.empty()) {
            ListNode* temp = mys.top();
            mys.pop();
            s->next = temp;
            s = temp;
        }
        return;
    }
};