Insertion Sort List 分类： Leetcode（排序） 2015-04-09 11:26 23人阅读 评论(0) 收藏

Insertion Sort List

 Sort a linked list using insertion sort.

很简单的一道题，思路跟数组的插入排序一样

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode *insertionSortList(ListNode *head) {
        ListNode dummy(INT_MIN);
        
        for (ListNode * cur =head; cur != nullptr;) {
            ListNode * pos = findInsertPos(&dummy, cur->val);
            ListNode *tmp = cur->next;
            cur->next = pos->next;
            pos->next = cur;
            cur = tmp;
        }
        return dummy.next;
    
    }
    
    ListNode* findInsertPos(ListNode *head, int x) {
        ListNode *pre = nullptr;
        ListNode *cur =head;
        while(cur &&cur->val <=x) {
            pre = cur;
            cur = cur->next;
        }
        return pre;
    }
};

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