[leetcode] Partition List

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Partition List

分成两个链表，一个比x小，一个比x大，然后再拼接。

#include "iostream"using namespace std;/**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 (head==NULL) {            return NULL;        }                //cout<<head->val<<endl;                ListNode *small=new ListNode(0);        ListNode *big=new ListNode(0);        ListNode *p=small;        ListNode *q=big;        ListNode *current=head;                //cout<<current->val<<endl;                while (current!=NULL) {            if (current->val<x) {                p->next=current;                current=current->next;//切记，不能使用current++！！！                p=p->next;            }else{                q->next=current;                current=current->next;                q=q->next;            }        }                if (p==small||q==big) {//都比x大or小            return head;        }                //连接两个串                p->next=big->next;        q->next=NULL;        current=small->next;                //记得释放内存        free(small);        free(big);                return current;                    }};int main() {    ListNode *t=new ListNode(1);    t->next=new ListNode(2);    cout<<t->val<<endl;    Solution so;    ListNode *res= so.partition(t, 2);    cout<<res->val<<res->next->val<<endl;    return 0;}

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