Partition List 分类： Leetcode（链表） 2015-03-03 21:13 29人阅读 评论(0) 收藏

Partition List T
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) {
        ListNode left_dummy(-1);
        ListNode right_dummy(-1);
        
        ListNode* left_cur = &left_dummy;
        ListNode* right_cur = &right_dummy;
        
        for (ListNode *cur = head;cur ; cur = cur->next) {
            if(cur->val < x) {
                left_cur->next = cur;
                left_cur = cur;
            } else {
                right_cur->next = cur;
                right_cur =cur;
            }
            
        }
        
        left_cur->next = right_dummy.next;
        right_cur->next = NULL;
        return left_dummy.next;
    }
    
};

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