合并两个已排序单链表

最新推荐文章于 2021-05-23 16:38:41 发布

原创最新推荐文章于 2021-05-23 16:38:41 发布 · 740 阅读

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一、保留重复元素

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
ListNode *mergeTwoLists(ListNode *list1,ListNode *list2)
{
    ListNode dummy(-1); 
    for(ListNode *p = &head;list1 != nullptr || list2 != nullptr;p=p->next)
    {
        int val1 = list1==nullptr?INT_MAX:list1->val;
        int val2 = list2==nullptr?INT_MAX:list2->val;
        if(val1 <= val2)
        {
            p->next = list1;
            list1 = list1->next;
        }
        else
        {
            p->next = list2;
            list2 = list2->next;
        }
    }
    return dummy.next;
}

二、去除重复元素

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
ListNode *mergeTwoLists(ListNode *list1,ListNode *list2)
{
    ListNode dummy(-1); 
    for(ListNode *p = &head;list1 != nullptr || list2 != nullptr;p=p->next)
    {
        int val1 = list1==nullptr?INT_MAX:list1->val;
        int val2 = list2==nullptr?INT_MAX:list2->val;
        if(val1 < val2)
        {
            p->next = list1;
            list1 = list1->next;
        }
        else if(val1 > val2)
        {
            p->next = list2;
            list2 = list2->next;
        }
        else
        {
            p->next = list1; //p->next = list2;
            list1 = list1->next;
            list2 = list2->next;
        }
    }
    return dummy.next;
}