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 ) {

    if (pHead1 == NULL) {
        return pHead2;
    }
    if (pHead2 == NULL) {
        return pHead1;
    }

    struct ListNode* mergedhead = NULL;
    struct ListNode* temp = NULL;

    if (pHead1->val <= pHead2->val) {
        mergedhead = pHead1;
        pHead1 = pHead1->next;
    } else {
        mergedhead = pHead2;
        pHead2 = pHead2->next;
    }
    temp = mergedhead;

    while (pHead1 != NULL && pHead2 != NULL) {

        if (pHead1->val <= pHead2->val) {
            mergedhead->next = pHead1;
            pHead1 = pHead1->next;
        } else {
            mergedhead->next = pHead2;
            pHead2 = pHead2->next;
        }
        mergedhead = mergedhead->next;
    }

    if (pHead1 != NULL) {
        mergedhead->next = pHead1;
    }
    if (pHead2 != NULL) {
        mergedhead->next = pHead2;
    }
    return temp;
}