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
 */
#include <stdlib.h>
struct ListNode* Merge(struct ListNode* pHead1, struct ListNode* pHead2 ) {
    // write code here
   
    if (pHead1 == NULL) {
        return pHead2;
    }
    if (pHead2 == NULL) {
        return pHead1;
    }
    
    struct ListNode *dummy = malloc(sizeof(struct ListNode));
    struct ListNode *tail = dummy;

    while((pHead1!= NULL)&&(pHead2 != NULL)) {
        if (pHead1->val <= pHead2->val) {
           tail->next = pHead1;
           pHead1 = pHead1->next;
        }
        else {
            tail->next = pHead2;
            pHead2 = pHead2->next;
        }
        tail = tail->next;
    }
    tail->next = (pHead1 != NULL) ? pHead1 : pHead2;
    struct ListNode *result = dummy->next;
    free(dummy);
    return result;
}