比如：
输入：1->2->4, 1->3->4
输出：1->1->2->3->4->4

#include <stdio.h>
#include <stdlib.h>typedef struct Node {int data;struct Node* next;
} Node, *LinkedList;// 创建一个新节点
Node* createNode(int data) {Node* newNode = (Node*)malloc(sizeof(Node));if (newNode == NULL) {printf("Error! Unable to create a new node.\n");exit(0);}newNode->data = data;newNode->next = NULL;return newNode;
}// 在链表末尾添加新节点
void append(LinkedList* head, int data) {if (*head == NULL) {*head = createNode(data);}else {Node* lastNode = *head;while (lastNode->next != NULL) {lastNode = lastNode->next;}lastNode->next = createNode(data);}
}// 打印链表
void printList(LinkedList head) {while (head != NULL) {printf("%d ", head->data);head = head->next;}printf("\n");
}LinkedList mergeTwoLists(Node* head1, Node* head2)
{if (head1 == NULL){return head2;}if (head2 == NULL){return head1;}Node *newList = NULL;Node *curList = NULL;newList = curList = (Node *)malloc(sizeof(Node));while (head1 && head2){if (head1->data > head2->data){curList->next = head2;head2 = head2->next;}else{curList->next = head1;head1 = head1->next;}curList = curList->next;}if (head1){curList->next = head1;}else{curList->next = head2;}Node* p = newList;newList = newList->next;free(p);   //释放申请的空间return newList;
}int main() {LinkedList head1 = NULL;append(&head1, 1);append(&head1, 3);append(&head1, 4);append(&head1, 6);LinkedList head2 = NULL;append(&head2, 1);append(&head2, 2);append(&head2, 5);append(&head2, 7);printf("Original List1: ");printList(head1);printf("Original List2: ");printList(head2);LinkedList head = mergeTwoLists(head1, head2);printf("mergeTwoLists List: ");printList(head);system("pause");return 0;
}

这个是比较详细的说明：https://mp.weixin.qq.com/s/0TiG9cF_la77aW_jUZf53w

CSDN：https://blog.csdn.net/efls111/article/details/134351938