Leetcode Sort List

来源：互联网发布：cocos2d js 教程 mac 编辑：程序博客网时间：2024/05/08 22:13
题意：将链表排序。
思路：使用归并排序。
/** * Definition for singly-linked list. * struct ListNode { *     int val; *     ListNode *next; *     ListNode(int x) : val(x), next(NULL) {} * }; */class Solution {public:    vector<ListNode*> mylist;    ListNode* sortList(ListNode* head) {        if(head == NULL) return head;        ListNode* next = head;        while(next) {            mylist.push_back(next);            next = next->next;        }                next = mysort(0, mylist.size() - 1);                return next;    }        ListNode* mysort(int low, int high) {        if(low == high) {            mylist[low]->next = NULL;            return mylist[low];        }                int mid = low + (high - low) / 2;                ListNode* temp1 = mysort(low, mid); //if(temp1) cout << temp1->val << endl;        ListNode* temp2 = mysort(mid + 1, high); //if(temp2) cout << temp2->val << endl;        cout << endl;                ListNode* myhead = new ListNode(0);        ListNode* next = myhead;                while(temp1 || temp2) {            ListNode* tempnext = NULL;            if(temp1 && temp2) {                if(temp1->val < temp2->val) {                    tempnext = temp1;                    temp1 = temp1->next;                                    }                else {                    tempnext = temp2;                    temp2 = temp2->next;                }                next->next = tempnext;                next = tempnext;                continue;            }            if(temp1 && !temp2) {                tempnext = temp1;                temp1 = temp1->next;                next->next = tempnext;                next = tempnext;                continue;            }            if(!temp1 && temp2) {                tempnext = temp2;                temp2 = temp2->next;                next->next = tempnext;                next = tempnext;                continue;            }        }        //next->next = NULL;        //show the list        /*        ListNode* testnext = myhead;        while(testnext) {            cout << testnext->val << " ";            testnext = testnext->next;        }        cout << endl;        */        next = myhead->next;        delete myhead;                return next;    }};
0 0