【LeetCode】Partition List

遍历链表将比给定值大或相等的节点移到一个新链表里面，最后新旧链表首尾想接即可。

/**
 * Definition for singly-linked list.
 * struct ListNode {
 * int val;
 * ListNode *next;
 * ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode *partition(ListNode *head, int x) {
        if(NULL==head) return NULL;
        ListNode *bigger_head=NULL;
        ListNode *bigger_curr=NULL;
        ListNode *curr=head;
        ListNode *pre=NULL;
        ListNode *re=head;
        while(curr)
        {
            if(curr->val>=x)
            {
                if(curr==re) re=curr->next;
                if(NULL==bigger_head) bigger_head=curr;
                if(pre) pre->next=curr->next;
                if(bigger_curr) bigger_curr->next=curr;
                bigger_curr=curr;
                curr=curr->next;
                continue;
            }
            pre=curr;
            curr=curr->next;
        }
        if(bigger_curr) bigger_curr->next=NULL;
        if(pre)pre->next=bigger_head;
        return re?re:bigger_head;
    }
};