Graph BFS

#include<stdio.h>
#include<stdlib.h>
#include<conio.h>
#define MAX_NODES 20
int visited[MAX_NODES];
int graph[MAX_NODES][MAX_NODES];
int i,j;
struct Queue {
    int front, rear, size;
    int capacity;
    int* array;
};

struct Queue* createQueue(int capacity) {
    struct Queue* queue = (struct Queue*)malloc(sizeof(struct Queue));
    queue->capacity = capacity;
    queue->front = queue->size = 0;
    queue->rear = capacity - 1;
    queue->array = (int*)malloc(queue->capacity * sizeof(int));
    return queue;
}

int isFull(struct Queue* queue) {
    return (queue->size == queue->capacity);
}

int isEmpty(struct Queue* queue) {
    return (queue->size == 0);
}

void enqueue(struct Queue* queue, int item) {
    if (isFull(queue)) return;
    queue->rear = (queue->rear + 1) % queue->capacity;
    queue->array[queue->rear] = item;
    queue->size = queue->size + 1;
}

int dequeue(struct Queue* queue) {
    int item;
    if (isEmpty(queue)) return -1;
    item = queue->array[queue->front];
    queue->front = (queue->front + 1) % queue->capacity;
    queue->size = queue->size - 1;
    return item;
}

void bfs(int start_node, int n) {
    struct Queue* queue = createQueue(n);
    visited[start_node] = 1;
    enqueue(queue, start_node);
    printf("BFS traversal starting from node %d: ", start_node);

    while (!isEmpty(queue)) {
	int current_node = dequeue(queue);
	printf("%d ", current_node);

	for (i = 0; i < n; i++) {
	    if (graph[current_node][i] && !visited[i]) {
		visited[i] = 1;
		enqueue(queue, i);
	    }
	}
    }
    free(queue);
}

int main() {
    int n,start_node;
    printf("Enter the number of nodes (Less than or equal to %d): ", MAX_NODES);
    scanf("%d", &n);

    printf("Enter the adjacency matrix (0 or 1):\n");
    for (i = 0; i < n; i++) {
	for (j = 0; j < n; j++) {
	    printf("i=%d, j=%d Enter: ",i,j);
	    scanf("%d", &graph[i][j]);
	}
    }
    printf("Enter the starting node for BFS: ");
    scanf("%d", &start_node);

    bfs(start_node, n);
    printf("\n");
    getch();
    return 0;
}