基于队列的环实现

基于自定义栈类实现。

package sort;

public class Queue_Array implements Queue{
    public static final int CAPACITY = 5;
    protected int capacity;
    protected Object[] q;
    protected int f = 0;
    protected int r = 0;

    public Queue_Array(int capacity) {
        this.capacity = capacity;
        this.q = new Object[capacity];
    }

    public Queue_Array() {
        this(CAPACITY);
    }


    @Override
    public int getSize() {
        return (capacity - (f - r)) % capacity;
    }

    @Override
    public boolean isEmpty() {
        return r == f;
    }

    @Override
    public Object front() throws Exception {
        if (isEmpty()) {
            throw new Exception();
        }
        return q[f];
    }

    @Override
    public void enqueue(Object o) {
        // 此处是避免和r == f时候的空冲突
        if (getSize() == capacity - 1) {
            return;
        }
        q[r] = o;
        r = (r + 1) % capacity;
    }

    @Override
    public Object dequeue() throws Exception {
        Object o;
        if (isEmpty()) {
            throw new Exception();
        }
        o = q[f];
        q[f] = null;
        f = (f + 1) % capacity;
        return o;
    }

    @Override
    public void traversal() {
        for (Object elem : q) {
            System.out.println(elem);
        }
    }
    public static Object Josephus(Queue q, int k) throws Exception {
        if (q.isEmpty()) {
            return null;
        }
        while (q.getSize() > 1) {
            q.traversal();
            for (int i = 0; i < k; i++) {
                q.enqueue(q.dequeue());
            }
            Object e = q.dequeue();
//            System.out.println("quit --- " + e);
        }
        return q.dequeue();
    }
    public static Queue buildQueue(Object[] a) {
        Queue q = new Queue_Array();
        for (Object item : a) {
            q.enqueue(item);
        }
        return q;
    }

    public static void main(String[] args) throws Exception {
        String[] kid = {
                "hufan", "libai", "dufu", "zhangzhidong", "wangbo"
        };
        System.out.println("final boy is ---" + Josephus(buildQueue(kid), 2));
    }
}

自己画了个烂图。

突然想到昨天没做题，今天快乐double。