牛客網，鏈表分割（C語言）

鏈接https://www.nowcoder.com/questionTerminal/0e27e0b064de4eacac178676ef9c9d70
來源：牛客網

編寫代碼，以給定值x爲基準將鏈表分割成兩部分，所有小於x的結點排在大於或等於x的結點之前 給定一個鏈表的頭指針 ListNode* pHead，請返回重新排列後的鏈表的頭指針。注意：分割以後保持原來的數據順序不變。

代碼：

/*
struct ListNode {
    int val;
    struct ListNode *next;
    ListNode(int x) : val(x), next(NULL) {}
};*/
class Partition {
public:
    ListNode* partition(ListNode* pHead, int x) {
        ListNode* cur = pHead;
        ListNode* lessHead,*lessTail,*greaterHead,*greaterTail;
        lessHead = lessTail = (ListNode*)malloc(sizeof(ListNode));
        greaterHead = greaterTail = (ListNode*)malloc(sizeof(ListNode));
        lessTail -> next = NULL;
        greaterTail -> next = NULL;
        while(cur != NULL)
        {
            if(cur->val < x)
            {
                lessTail -> next = cur;
                lessTail = cur;
            }
            else
            {
                greaterTail -> next = cur;
                greaterTail = cur;
            }
            cur = cur ->next;
        }
            lessTail -> next = greaterHead -> next;
            greaterTail ->next = NULL;
            ListNode* list = lessHead ->next;
            free(lessHead);
            free(greaterHead);
            return list;
         
    }
};