以升序将数字插入链表的C函数

#include <stdio.h>
#include <stdlib.h>

// 定义链表节点结构体
struct ListNode {
    int val;
    struct ListNode *next;
};

// 创建新节点
struct ListNode* createNode(int val) {
    struct ListNode* newNode = (struct ListNode*)malloc(sizeof(struct ListNode));
    newNode->val = val;
    newNode->next = NULL;
    return newNode;
}

// 插入数字到链表
struct ListNode* insert(struct ListNode* head, int val) {
    struct ListNode* newNode = createNode(val);
    
    // 头节点为空，直接将新节点作为头节点
    if (head == NULL) {
        head = newNode;
        return head;
    }
    
    // 头节点大于新节点，将新节点作为头节点
    if (head->val > val) {
        newNode->next = head;
        head = newNode;
        return head;
    }
    
    struct ListNode* curr = head;
    
    // 遍历链表找到合适的位置插入新节点
    while (curr->next != NULL && curr->next->val < val) {
        curr = curr->next;
    }
    
    newNode->next = curr->next;
    curr->next = newNode;
    
    return head;
}

// 打印链表
void printList(struct ListNode* head) {
    struct ListNode* curr = head;
    
    while (curr != NULL) {
        printf("%d ", curr->val);
        curr = curr->next;
    }
    
    printf("\n");
}

int main() {
    struct ListNode* head = NULL;
    
    // 插入数字到链表
    head = insert(head, 5);
    head = insert(head, 2);
    head = insert(head, 7);
    head = insert(head, 1);
    head = insert(head, 9);
    
    // 打印链表
    printList(head);
    
    return 0;
}