题解 | #合并两个排序的链表#

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 */
/**
 * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
 *
 * 
 * @param pHead1 ListNode类 
 * @param pHead2 ListNode类 
 * @return ListNode类
 */
struct ListNode* Merge(struct ListNode* pHead1, struct ListNode* pHead2 ) {
    // write code here
    struct ListNode* p1 = pHead1;//用于遍历链表1
    struct ListNode* p2 = pHead2;//用于遍历链表2
    struct ListNode* pHead3 = (struct ListNode*)malloc(sizeof(struct ListNode));//暂时的头结点
    pHead3->next = NULL;
    struct ListNode* p3 = pHead3;//用于遍历链表3
    while(p1 != NULL && p2 != NULL){
        if(p1->val <= p2->val){
            p3->next = p1;
            p3 = p1;
            p1 = p1->next;
        }
        else{
            p3->next = p2;
            p3 = p2;
            p2 = p2->next;
        }
    }
    if(p1){
        p3->next = p1;
    }
    else{
        p3->next = p2;
    }
    return pHead3->next;//这里是暂时头结点的用处
}