题解 | #合并两个排序的链表#

/**设置哑变量解决
 * 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* p;
    struct ListNode* q;
    struct ListNode* pre;
    struct ListNode* dummy =(struct ListNode*)malloc(sizeof(struct ListNode));
    dummy ->next =  NULL;
    pre = dummy;
    p = pHead1;
    q = pHead2;
    while(p!=NULL && q!=NULL){
        if(p->val>q->val){
            pre ->next =  q;
            q = q->next;  
        }else{
            pre ->next = p;
            p = p->next;
        }
        pre = pre->next;
    }
    while(p!=NULL){
        pre ->next =  p;
        p = p->next;
        pre = pre->next;
    }
    while(q!=NULL){
        pre ->next =  q;
        q = q->next;
        pre = pre->next;
    }
    pre ->next =  NULL;
    return dummy->next;
}