Breadth First Search

BreadthFirstSearchStructure.java

boolean[] visited = new boolean[n];
Deque<Integer> queue = new LinkedList();
queue.offer(0);
while(!queue.isEmpty()) {
    int x = queue.poll();
    // do something to generate the output of your algorithm
    // or just return x if that's what you are searching for
    visited[x] = true;
    int[] nextElements = getElementsAssessibleFromX(x);
    for(int y: nextElements) {
        if(!visited[y]) {
            queue.offer(y);
        }
    }
}