numWithin

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "Graph.h"
#include "Queue.h"

/*BFS, but uses a dist array to keep track of the distances of vertices
when they are found. You could use the visited array as the dist array, like
what I did in furthestReachable. */
int numWithin(Graph g, int src, int dist) {
    int n = GraphNumVertices(g);
    int visited[n];
    memset(visited, -1, sizeof(int) * n);
    visited[src] = src;
    int distA[n];
    distA[src] = 0;
    int ret = 0;
    Queue q = QueueNew();
    QueueEnqueue(q, src);
    while (!QueueIsEmpty(q)) {
        int v = QueueDequeue(q);
        if (distA[v] <= dist) {
            ret++;
        }

        for (int i = 0; i < n; i++) {
            if (visited[i] == -1 && GraphIsAdjacent(g, i, v)) {
                QueueEnqueue(q, i);
                visited[i] = v;
                distA[i] = distA[v] + 1;

            }
        }
    }
    QueueFree(q);
    return ret;
}