请用C语言设计一个非常简单的算法，实现单链表反转

以下是一个更简单的C语言实现单链表反转的算法：

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

typedef struct ListNode {
    int val;
    struct ListNode *next;
} ListNode;

ListNode* reverseList(ListNode* head) {
    ListNode *prev = NULL, *curr = head;
    while (curr != NULL) {
        ListNode *next = curr->next;
        curr->next = prev;
        prev = curr;
        curr = next;
    }
    return prev;
}

int main() {
    ListNode *head = (ListNode*)malloc(sizeof(ListNode));
    head->val = 1;
    head->next = (ListNode*)malloc(sizeof(ListNode));
    head->next->val = 2;
    head->next->next = (ListNode*)malloc(sizeof(ListNode));
    head->next->next->val = 3;
    head->next->next->next = NULL;
    
    printf("Original list: ");
    ListNode *curr = head;
    while (curr != NULL) {
        printf("%d ", curr->val);
        curr = curr->next;
    }
    printf("\n");

    head = reverseList(head);
    
    printf("Reversed list: ");
    curr = head;
    while (curr != NULL) {
        printf("%d ", curr->val);
        curr = curr->next;
    }
    printf("\n");
    
    return 0;
}

该算法与之前的算法类似，但是省去了一个指针变量，直接在while循环内部定义了一个指向下一个节点的指针变量next。这样可以使代码更加简洁。