CS153/hw6/hw5programs/burowski_bfs.oat

global debug = false;

struct Node {
	string val;
	bool visited;
	Queue neighbors;
	bool hasNext
}

struct QNode {
	Node node;
	QNode next;
	bool qhasNext
}

struct Queue {
	QNode head;
	QNode tail;
	int size
}

Node getIthInQueue(int i, Queue q) {
	var tmp = q.head;
	if (i + 1 == q.size) {
		return q.tail.node;
	}
	while (tmp.qhasNext) {
		if (i == 0) {
			return tmp.node;
		}
		tmp = tmp.next;
		i = i - 1;
	}
	return newNode("ERROR");
}

Node newNode(string v) {
	return new Node {val=v; hasNext=false; visited=false; neighbors=newEmptyQueue()};
}

QNode newQNode(Node n) {
	return new QNode {node=n; next=QNode null; qhasNext=false};
}

void printNode(Node n) {
	print_string(n.val);
	return;
}

Queue newEmptyQueue() {
	return new Queue {head=QNode null; tail=QNode null; size=0};
}


bool isEmpty(Queue q) {
	return q.size == 0;	
}

void printNeighbors(Node n) {
	printNeighborsDebug(n, debug);
	return;
}

void printNeighborsDebug(Node n, bool d) {
	if (!d) {
		return;
	}
	var s = n.neighbors.size;
	for (var i = 0; i < s; i = i + 1;) {
		var x = getIthInQueue(i, n.neighbors);
		printNode(x);
	}
	print_string("\n");
	return;
}

void enqueue(Queue q, Node n) {
	var node = newQNode(n);
	if (q.size == 0) {
		q.head = node;
	} else {
		q.tail.qhasNext = true;
		q.tail.next = node;
	}
	q.size = q.size + 1;
	node.qhasNext = false;
	q.tail = node;
	return;
}

Node dequeue(Queue q) {
	if (isEmpty(q)) {
		return newNode("");
	}
	var tmp = q.head;
	q.head = tmp.next;
	q.size = q.size - 1;
	return tmp.node;
}

void addNeighbor(Node tgt, Node toAdd) {
	enqueue(tgt.neighbors, toAdd);
	return;
}

void bfs(Node start) {
	var q = newEmptyQueue();
	start.visited = true;
	enqueue(q, start);
	while (!isEmpty(q)) {
		var curr = dequeue(q);
		printNode(curr);
		var s = curr.neighbors.size;
		for (var i = 0; i < s; i = i + 1;) {
			var n = getIthInQueue(i, curr.neighbors);
			if (!(n.visited)) {
				n.visited = true;
				enqueue(q, n);
			}
		}
	}
	return;
}


void print_debug(string msg) {
	if (!debug) {
		return;
	}
	print_string(msg);
	return;
}

int program (int argc, string[] argv) {

	var there = newNode("there ");
	var should = newNode("should ");
	var be = newNode("be ");
	var better = newNode("better ");
	var food = newNode("food ");
	var options = newNode("options ");
	var on = newNode("on ");
	var campus = newNode("campus");

	addNeighbor(there, should);
	addNeighbor(there, be);
	addNeighbor(there, better);
	
	addNeighbor(should, there);
	addNeighbor(should, food);
	
	addNeighbor(be, there);
	addNeighbor(be, better);
	

	addNeighbor(better, there);
	addNeighbor(better, be);
	addNeighbor(better, options);
	
	addNeighbor(food, should);
	addNeighbor(food, options);
	
	addNeighbor(options, food);
	addNeighbor(options, better);
	addNeighbor(options, on);
	addNeighbor(options, campus);
	
	addNeighbor(on, options);
	
	addNeighbor(campus, options);
	
	bfs(there);
	return 0; 	
}