Java每日一练01素数，删除倒数第n个索引，外观数组

• 打印1-100之间的素数
• 链表删除倒数第n个索引的元素
• 外观数组

class Solution{
    public static void main(String[] args) {
        for (int i = 0; i < 100; i++) {
            boolean b = new Test102().checkPrime(i);
            if (b) System.out.print(i + " ");
            // 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97
        }
    }

    private boolean checkPrime(int x) {
        boolean isPrime = true;
        if (x == 1 || x % 2 == 0 && x != 2) {
            isPrime = false;
        } else {
            for (int i = 3; i < x; i++) {
                if (x % i == 0) {
                    isPrime = false;
                    break;
                }
            }
        }
        return isPrime;
    }
}

class Node {
    int data;
    Node next;
    public Node() {
    }

    public Node(int data) {
        this.data = data;
    }
}

class link implements Commonlink,linkUtils {
    Node head, tail;
    int size;

    public link() {
        head = new Node();
        tail = head;
        size = 0;
    }

    
    @Override
    public void add(int e) {
        // TODO Auto-generated method stub
        Node node = new Node(e);
        tail.next = node;
        tail = node;
        size++;
    }

    
    @Override
    public void insert(int e, int index) {//形参index表示结点所处位置的下标
        Node node1 = getNodePrePosition(index);
        Node node = getNodePosition(index);
        //创建一个新节点，为要插入的节点
        Node node2 = new Node(e);
        if (index == 0) {//如果插入的位置是第一个节点
            head.next = null;
            head.next = node2;
        } else {
            node1.next = null;
            node1.next = node2;
        }
        node2.next = node;
        size++;

    }

    
    private Node getNodePosition(int index) {
        checkindex(index);
        Node node = head.next;
        for (int i = 0; i < index; i++) {
            node = node.next;
        }
        return node;
    }

    
    private Node getNodePrePosition(int index) {
        checkindex(index);
        //找到下标index-1
        Node node1 = head.next;
        for (int i = 0; i < index - 1; i++) {
            node1 = node1.next;
        }
        return node1;
    }

    
    @Override
    public void delete(int index) {
        Node node1 = getNodePrePosition(index);
        Node node = getNodePosition(index);
        if (index != 0) {
            if (index == size - 1) {
                node1.next = null;
            } else {
                node1.next = null;
                node1.next = node.next;
            }
            //设置node的指针为空，node的值为空
            node.next = null;
            node.data = 0;
        } else {//假设index等于0
            head.next = null;
            head.next = node.next;
            node.next = null;
            node.data = 0;
        }
        size--;
    }

    
    @Override
    public int get(int index) {
        // TODO Auto-generated method stub
        //找到下表index
        Node node = head.next;
        //从头节点开始，依次向后查找
        for (int i = 0; i < index; i++) {
            node = node.next;
        }
        return node.data;
    }

    
    @Override
    public void modify(int e, int index) {
        // TODO Auto-generated method stub
        //找到下表index
        Node node = head.next;
        //从头节点开始，依次向后查找
        for (int i = 0; i < index; i++) {
            node = node.next;
        }
        Node node1 = new Node(e);
        node.data = e;
    }

    
    @Override
    public int getSize() {
        return size;
    }

    
    public void checkindex(int index) {
        if (index < 0 || index > size) {
            throw new IndexOutOfBoundsException("invalid param");
        }
    }

    
    @Override
    public void printlink(link link) {
        for (int i = 0; i < link.getSize(); i++) {
            //取出元素
            int e = link.get(i);
            //输出元素
            System.out.println("No " + i + " data： " + e);
        }
    }

    
    @Override
    public void deleteCountDownIndex(link link,int index) {
        int newIndex = link.getSize() - index;
        link.delete(newIndex);
    }

    
    @Override
    public Node reverselink() {
        Node prev = null; 
        Node curr = head; 
        while (curr != null) {
            Node nextTemp = curr.next; 
            curr.next = prev; 
            prev = curr; 
            curr = nextTemp; 
        }
        return prev;
    }
}

interface Commonlink {
    //存储
    public void add(int e);

    //插入
    public void insert(int e, int index);

    //删除
    public void delete(int index);

    //获取元素
    public int get(int index);

    //修改
    public void modify(int e, int index);

    //获取元素个数
    public int getSize();

    //遍历链表
    public void printlink(link link);
}

interface linkUtils {
    // 删除倒数第n个索引的节点
    public void deleteCountDownIndex(link link,int index);
    // 反转链表
    public Node reverselink();
}

class Test {
    public static void main(String[] args) {
        link link = new link();
        //添加数据
        link.add(12);
        link.add(34);
        link.add(56);
        link.add(78);
        link.add(90);
        //遍历列表
        // link.printlink(link);
        link.deleteCountDownIndex(link,4);
        link.printlink(link);
    }
}

class Solution1 {
    

    
    public String countAndSay(int n) {
        if(n == 1) return "1";
        
        String num = countAndSay(n - 1);
        StringBuilder s = new StringBuilder();
        for(int i=0; i