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
    if(pHead1 == NULL) return pHead2;
    if(pHead2 == NULL) return pHead1;
    //创建虚拟节点，简化操作
    struct ListNode * dummy = (struct ListNode*)malloc(sizeof(struct ListNode));
    dummy ->val = -1;
    dummy ->next = NULL;
    struct ListNode *curr = dummy;
    while(pHead1 != NULL && pHead2 != NULL){
        if(pHead1 ->val <= pHead2 ->val){
            curr ->next = pHead1;
            pHead1 = pHead1 ->next;
        }else{
            curr ->next = pHead2;
            pHead2 = pHead2 -> next;
        }
        curr = curr ->next;
    }
    if(pHead1 != NULL){
        curr ->next = pHead1;
    }
    if(pHead2 != NULL){
        curr ->next = pHead2;
    }
    struct ListNode *result = dummy ->next;
    free(dummy);
    return result;
}