NC_131_GetMedian NC_132_Joseph_circle NC_133_ODDEVENLIST

package org.example.interview.practice;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Objects;

/**
 * @author xianzhe.ma
 * @date 2021/11/3
 */

public class NC_131_GetMedian {

    private List list;

    public void Insert(Integer num) {
        if (Objects.isNull(list)) {
            list = new ArrayList<>();
        }

        list.add(num);
        Collections.sort(list);

    }

    public Double GetMedian() {

        Integer[] array = new Integer[list.size()];
        list.toArray(array);

        int size = list.size();
        if (size % 2 == 1) {
            return array[size/2]/1.0;
        } else {
            int num1 = array[size/2-1];
            int num2 = array[size/2];
            return (num1 + num2)/2.0;
        }
    }
}

package org.example.interview.practice;

import java.util.ArrayList;

/**
 * @author xianzhe.ma
 * @date 2021/11/4
 */

public class NC_132_Joseph_circle {

    public int ysf (int n, int m) {
        // write code here
        // write code here
        ArrayList list = new ArrayList();
        // 先构造该数组序列
        for(int i = 1; i <= n; i++){
            list.add(i);
        }
        // 第一次从索引为0处进行报数
        int id = 0;
        // 直到剩最后一个人的时候停止循环
        while(n > 1){
            // 从开始报数的索引处向后数m-1个人即是被淘汰的人的索引处
            id = (id + m -1) % n;
            // 将被淘汰的人删除掉
            list.remove(id);
            // 将人数减1
            n--;
        }
        // 最后剩下的一个人即是最终的获胜者
        return list.get(0);

    }
}

package org.example.interview.practice;

import java.util.Objects;

/**
 * @author xianzhe.ma
 * @date 2021/8/1
 */

public class NC_133_ODDEVENLIST {

    public static void main (String[] args) {
        ListNode node1 = new ListNode(1);
        ListNode node2 = new ListNode(4);
        ListNode node3 = new ListNode(6);
        ListNode node4 = new ListNode(3);
        ListNode node5 = new ListNode(7);
        node1.next = node2;
        node2.next = node3;
        node3.next = node4;
        node4.next = node5;

        ListNode res = oddEvenList(node1);
        while (res != null) {
            System.out.println(res.val);
            res = res.next;
        }
    }
    public static ListNode oddEvenList (ListNode head) {
        // write code here
        if (Objects.isNull(head))
            return null;
        ListNode oddHead = null;
        ListNode oddTail = null;
        ListNode evenHead = null;
        ListNode evenTail = null;
        int i = 1;
        while (head != null) {
            if (i%2 != 0) {
                if (oddHead == null) {
                    ListNode cur = new ListNode(head.val);
                    oddHead = cur;
                    oddTail = cur;
                } else {
                    ListNode cur = new ListNode(head.val);
                    oddTail.next = cur;
                    oddTail =  oddTail.next;
                }
            } else {
                if (evenHead == null) {
                    ListNode cur = new ListNode(head.val);
                    evenHead = cur;
                    evenTail = cur;
                } else {
                    ListNode cur = new ListNode(head.val);
                    evenTail.next = cur;
                    evenTail =  evenTail.next;
                }
            }
            i++;
            head = head.next;
        }

        oddTail.next = evenHead;
        return oddHead;
    }

    public static class ListNode {
        int val;
        ListNode next = null;

        public ListNode(int val) {
            this.val = val;
        }
    }
}