LeetCode21——Merge Two Sorted Lists

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.

难度系数：

容易

实现

[code]ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {
    ListNode *newnode = NULL;
    ListNode *node1 = NULL;
    ListNode *node2 = NULL;
    if (l1 == NULL)
        return l2;
    else if (l2 == NULL)
        return l1;
    else if (l1->val > l2->val) {
        newnode = l2;
        node1 = l1;
        node2 = l2->next;
    } else {
        newnode = l1;
        node1 = l1->next;
        node2 = l2;
    }
    ListNode *node = newnode;
    while (true) {
        if (node1 == NULL) {
            node->next = node2;
            break;
        }
        if (node2 == NULL) {
            node->next = node1;
            break;
        }
        if (node1->val > node2->val) {
            node->next = node2;
            node2 = node2->next;
        } else {
            node->next = node1;
            node1 = node1->next;
        }
        node = node->next;
    }
    return newnode;
}