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Partition List

Given a linked list and a value x, partition it such that all nodes less than x come before nodes greater than or equal to x.

You should preserve the original relative order of the nodes in each of the two partitions.

For example,
Given 1->4->3->2->5->2 and x = 3,
return 1->2->2->4->3->5.

/** * 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;        ListNode *small, *big, *shead, *bhead;        shead = (ListNode *)malloc(sizeof(ListNode));        bhead = (ListNode *)malloc(sizeof(ListNode));        shead->next = bhead->next = NULL;        small = shead;        big = bhead;        while(head != NULL){            if(head->val >= x){                ListNode *tmp = (ListNode *)malloc(sizeof(ListNode));                tmp->val = head->val;                tmp->next = NULL;                big->next = tmp;                big = tmp;            }            else {                ListNode *tmp = (ListNode *)malloc(sizeof(ListNode));                tmp->val = head->val;                tmp->next = NULL;                small->next = tmp;                small = tmp;            }            head = head->next;        }        small->next = bhead->next;        return shead->next;    }};

 

Partition List