#21. Merge Two Sorted Lists

Work_Life

于 2017-09-05 09:15:28 发布

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分类专栏： Leetcode刷题

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本文介绍了一种方法来合并两个已排序的链表，并通过重新连接节点的方式创建一个新的排序链表。该方法适用于计算机科学与数据结构的学习者。

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题目描述：

Merge two sorted linked lists and return it as a new list. The new list should be made by splicing together the nodes of the first two lists.

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     ListNode *next;
 *     ListNode(int x) : val(x), next(NULL) {}
 * };
 */
class Solution {
public:
    ListNode* mergeTwoLists(ListNode* l1, ListNode* l2) {
        ListNode *temp=l2,*last_temp=NULL,*random;
        while(l1!=NULL){
            temp = l2;
            while(temp!=NULL&&l1->val>temp->val){
                last_temp = temp;
                temp = temp->next;
            }
            /*if(last_temp!=NULL)
                cout<<"last_temp = "<<last_temp->val<<endl;
            if(temp!=NULL)
                cout<<"temp ="<<temp->val<<endl;
                */
            random = l1;
            l1 = l1->next;
            //插入头 
            if(last_temp==NULL){    
                random->next = l2;
                l2 = random;
            }else if(temp==NULL){//插入尾部 
                last_temp->next = random;
                random->next = NULL;
            }else if(temp!=NULL){//插入中间 
                last_temp->next=random;
                random->next = temp;
            }

            random = l2;
            while(random!=NULL){
                //cout<<random->val<<"  ";
                random = random->next;
            } 
            //cout<<endl;
        }
        return l2;
    }
};