合并两个排序的链表

/**
 * struct ListNode {
 *	int val;
 *	struct ListNode *next;
 * };
 *
 * C语言声明定义全局变量请加上static，防止重复定义
 */

/**
 * 
 * @param pHead1 ListNode类 
 * @param pHead2 ListNode类 
 * @return ListNode类
 */
struct ListNode* Merge(struct ListNode* pHead1, struct ListNode* pHead2 ) {
    // write code here
    if(pHead1==NULL)
        return pHead2;
    if (pHead2==NULL)
        return pHead1;
    struct ListNode *temp = malloc(sizeof(struct ListNode));
    temp->next=NULL;
    if(pHead1->val<=pHead2->val){
        temp=pHead1;
        temp->next=Merge(pHead1->next,pHead2);
    }
    else{
        temp=pHead2;
        temp->next=Merge(pHead1,pHead2->next);
    }
    return temp;
}