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#include <stdio.h>
#include <stdlib.h>
#include "llist.h"
#include "list.h"
#define N 100

#ifdef LLIST_SOL

static struct node *node_alloc(int elem) {
	struct node *tmp = (struct node *)malloc(sizeof(struct node));

	if (tmp != NULL) {
		tmp->elem = elem;
		tmp->next = NULL;
	}
	return tmp;
}
static int node_delete(struct node *L) {
	if (L == NULL || L->next == NULL) {
		return 1;
	}
	else {
		struct node *tmp = L->next;
		L->next = tmp->next;
		free(tmp);
		return 0;
	}
}
static int node_insert(struct node *L, int elem) {
	if (L == NULL) {
		return 1;
	}
	else {
		struct node *tmp = node_alloc(elem);

		if (tmp != NULL) {
			tmp->next = L->next;
			L->next = tmp;
		}
		return tmp == NULL;
	}
}

static struct node *node_search(struct node *L, unsigned int i) {
	while (i-- > 0 && L != NULL)
		L = L->next;
	return L;
}




/*inverte l'ordine della lista*/
void list_invert(list *L) {
	int n = list_length(*L);
	int i, scambio;
	struct node *tmp1, *tmp2;

	for (i = 0; i < n / 2; i++) {
		tmp1 = node_search(*L, i);
		tmp2 = node_search(*L, n-1-i);
		scambio = tmp1->elem;
		tmp1->elem = tmp2->elem;
		tmp2->elem = scambio;
	
	}

}






/*inverte l'ordine della lista*/
void list_invert2(list *L) {
	struct node *tmp, *tmp1, *tmp2;
	if (L != NULL && *L != NULL && (*L)->next != NULL) {
		tmp1 = *L;
		tmp2 = tmp1->next;
		tmp1->next = NULL;
		while (tmp2 != NULL) {
			tmp= tmp2->next;
			tmp2->next = tmp1;
			tmp1 = tmp2;
			tmp2 = tmp;
		}
		*L = tmp1;
	}
	
}



/*ritorna l'elemento che si trova nel posto mediano della lista*/
int middle_select(list L) {
	return indx_select(&L, list_length(L) / 2);
}


int middle_select2(list L) {
	struct node *tmp = L;
	struct node *tmp2 = L;
	while (tmp2 != NULL && tmp2->next != NULL) {
		tmp = tmp->next;
		tmp2 = tmp2->next->next;
	}

	return tmp->elem;

}

/*ritorna la lunghezza della lista*/

int list_length(list L) {
	int len=0;
	while (L != NULL) {
		len++;
		L = L->next;
	}
	return len;

}



//elimina gli elementi in posizione dispari 
int odd_delete(list *L) {
	int i=0;
	struct node*tmp = *L;
	while (tmp != NULL) {
		node_delete(tmp);
		i++;
		tmp = tmp->next;
	}
	return i;

}

//elimina gli elementi in posizione pari 
int even_delete(list *L) {
	int i = 1;
	struct node*tmp = *L;
	*L = (*L)->next;
	free(tmp);
	i+=odd_delete(L);
	return i;

}







/*stampa elementi e relativa posizione */
void list_ordprint(list L) {
	int i = 0;
	
	while (L != NULL) {
		printf("(%d,%d) ", i++, L->elem);
		L = L->next;
	}
	printf("\n");
}



/*salva elementi su file */
void list_save(list L, char *filename) {
	FILE* outF = fopen(filename, "w");
	while (L != NULL) {
		fprintf(outF, "%d ", L->elem);
		L = L->next;
	}
	printf("\n");
	fclose(outF);
}



/*carica elementi da file */
void list_load(list *L, char *filename) {
	FILE* inF = fopen(filename, "r");
	int i=1;
	while (fscanf(inF, "%d ", &i)>0) {
		tail_insert(L, i);
	}
	fclose(inF);
}

#endif