Deque implementation in c
// Deque implementation in C
#include <stdio.h>
#define MAX 10
void addFront(int *, int, int *, int *);
void addRear(int *, int, int *, int *);
int delFront(int *, int *, int *);
int delRear(int *, int *, int *);
void display(int *);
int count(int *);
int main() {
int arr[MAX];
int front, rear, i, n;
front = rear = -1;
for (i = 0; i < MAX; i++)
arr[i] = 0;
addRear(arr, 5, &front, &rear);
addFront(arr, 12, &front, &rear);
addRear(arr, 11, &front, &rear);
addFront(arr, 5, &front, &rear);
addRear(arr, 6, &front, &rear);
addFront(arr, 8, &front, &rear);
printf("\nElements in a deque: ");
display(arr);
i = delFront(arr, &front, &rear);
printf("\nremoved item: %d", i);
printf("\nElements in a deque after deletion: ");
display(arr);
addRear(arr, 16, &front, &rear);
addRear(arr, 7, &front, &rear);
printf("\nElements in a deque after addition: ");
display(arr);
i = delRear(arr, &front, &rear);
printf("\nremoved item: %d", i);
printf("\nElements in a deque after deletion: ");
display(arr);
n = count(arr);
printf("\nTotal number of elements in deque: %d", n);
}
void addFront(int *arr, int item, int *pfront, int *prear) {
int i, k, c;
if (*pfront == 0 && *prear == MAX - 1) {
printf("\nDeque is full.\n");
return;
}
if (*pfront == -1) {
*pfront = *prear = 0;
arr[*pfront] = item;
return;
}
if (*prear != MAX - 1) {
c = count(arr);
k = *prear + 1;
for (i = 1; i <= c; i++) {
arr[k] = arr[k - 1];
k--;
}
arr[k] = item;
*pfront = k;
(*prear)++;
} else {
(*pfront)--;
arr[*pfront] = item;
}
}
void addRear(int *arr, int item, int *pfront, int *prear) {
int i, k;
if (*pfront == 0 && *prear == MAX - 1) {
printf("\nDeque is full.\n");
return;
}
if (*pfront == -1) {
*prear = *pfront = 0;
arr[*prear] = item;
return;
}
if (*prear == MAX - 1) {
k = *pfront - 1;
for (i = *pfront - 1; i < *prear; i++) {
k = i;
if (k == MAX - 1)
arr[k] = 0;
else
arr[k] = arr[i + 1];
}
(*prear)--;
(*pfront)--;
}
(*prear)++;
arr[*prear] = item;
}
int delFront(int *arr, int *pfront, int *prear) {
int item;
if (*pfront == -1) {
printf("\nDeque is empty.\n");
return 0;
}
item = arr[*pfront];
arr[*pfront] = 0;
if (*pfront == *prear)
*pfront = *prear = -1;
else
(*pfront)++;
return item;
}
int delRear(int *arr, int *pfront, int *prear) {
int item;
if (*pfront == -1) {
printf("\nDeque is empty.\n");
return 0;
}
item = arr[*prear];
arr[*prear] = 0;
(*prear)--;
if (*prear == -1)
*pfront = -1;
return item;
}
void display(int *arr) {
int i;
printf("\n front: ");
for (i = 0; i < MAX; i++)
printf(" %d", arr[i]);
printf(" :rear");
}
int count(int *arr) {
int c = 0, i;
for (i = 0; i < MAX; i++) {
if (arr[i] != 0)
c++;
}
return c;
}
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