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

struct node {
    int i;
    struct node* next;
};

int rm_if(int i) {
    return i % 2;
}

void gen_list(struct node** head, int i) {
    if (i < 0)
        return;
    *head = (struct node*)malloc(sizeof(struct node));
    (*head)->i = i;
    (*head)->next = NULL;
    gen_list(&((*head)->next), i - 1);
}

void del_odd(struct node** head, int(*fn)(int)) {
    struct node** tmp;
    for (tmp = head; *tmp; ) {
        struct node* entry = *tmp;
        if (fn(entry->i)) {
            *tmp = entry->next;
            free(entry);
        } else
            tmp = &entry->next;
    }
} 

int main() {
    struct node** head, **tt;
    gen_list(head, 100);
    del_odd(head, rm_if);
    for (tt = head ; *tt;) {
        printf("%d ", (*tt)->i);
        tt = &((*tt)->next);
    }

    return 0;
}