91 lines
1.9 KiB
C
91 lines
1.9 KiB
C
#include <stdlib.h>
|
|
#include <stdio.h>
|
|
#include <assert.h>
|
|
|
|
typedef struct node {
|
|
struct node* next;
|
|
int data;
|
|
} node_t;
|
|
|
|
//could be only `last`; by definition, `head = last->next;`
|
|
typedef struct{
|
|
node_t* head;
|
|
node_t* last;
|
|
} CIRC;
|
|
|
|
//exo
|
|
CIRC mkcircular();
|
|
void insert(CIRC* cycle, int el);
|
|
node_t* extract(CIRC* cycle);
|
|
node_t* rotateToEven(CIRC* cycle);
|
|
node_t* rotateToOdd(CIRC* cycle);
|
|
|
|
void rotate(CIRC* cycle);
|
|
|
|
int main(void)
|
|
{
|
|
CIRC circ = mkcircular();
|
|
insert(&circ, 42);
|
|
insert(&circ, 21);
|
|
insert(&circ, 12);
|
|
|
|
printf("rotateToEven -> %d\n", rotateToEven(&circ)->data);
|
|
printf("rotateToOdd -> %d\n", rotateToOdd(&circ)->data);
|
|
printf("rotateToOdd -> %d\n", rotateToOdd(&circ)->data);
|
|
printf("rotateToEven -> %d\n", rotateToEven(&circ)->data);
|
|
|
|
printf("--------------------------\n");
|
|
printf("extract -> %d\n", extract(&circ)->data);
|
|
printf("extract -> %d\n", extract(&circ)->data);
|
|
printf("extract -> %d\n", extract(&circ)->data);
|
|
assert(!extract(&circ));
|
|
}
|
|
|
|
CIRC mkcircular(){
|
|
return (CIRC){};
|
|
}
|
|
|
|
void insert(CIRC* cycle, int el){
|
|
node_t* new = malloc(sizeof(node_t));
|
|
if(cycle->head == NULL)
|
|
cycle->head = cycle->last = new;
|
|
new->next = cycle->head;
|
|
new->data = el;
|
|
|
|
cycle->last->next = new;
|
|
cycle->last = new;
|
|
}
|
|
|
|
//problem with return node_t, it is the user that has to free the memory
|
|
//that he did not explicitly allocated...
|
|
node_t* extract(CIRC* cycle){
|
|
if(cycle->head == NULL || cycle->last == NULL)
|
|
return NULL;
|
|
node_t* ret = cycle->head;
|
|
if(cycle->head == cycle->last){
|
|
cycle->head = cycle->last = NULL;
|
|
return ret;
|
|
}
|
|
cycle->head = cycle->head->next;
|
|
cycle->last->next = cycle->head;
|
|
return ret;
|
|
}
|
|
|
|
void rotate(CIRC* cycle){
|
|
cycle->last = cycle->head;
|
|
cycle->head = cycle->head->next;
|
|
}
|
|
|
|
node_t* rotateToEven(CIRC* cycle){
|
|
while(cycle->head->data % 2 != 0)
|
|
rotate(cycle);
|
|
return cycle->head;
|
|
}
|
|
|
|
node_t* rotateToOdd(CIRC* cycle ){
|
|
while(cycle->head->data % 2 == 0)
|
|
rotate(cycle);
|
|
return cycle->head;
|
|
|
|
}
|