It's the homework of my college, implementing a function to reverse a simple one-way linked list. And I think this function I came up with was fun.

reverse.c

/*
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typedef struct reg {
    int ID;
    int score;
    struct reg *next;
} tReg;

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*/

void *_reverse_after(tReg *node) {
    void **p;
    if (node->next == NULL) {
        p = malloc(sizeof(void *) * 2);
        p[0] = node;    // tail
    } else {
        p = _reverse_after(node->next);
        *(tReg **)p[1] = node;
    }
    p[1] = &node->next;
    return p;
}

void reverse(tReg **head) {
    void **p = _reverse_after(*head);
    *head = p[0];
    *(tReg **)p[1] = NULL;
    free(p);
}

/*
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*/