Java每日一练(20230409) 多数元素、反转链表 II 、日期之间的遍历

import java.util.*;
public class majorityElement {
    public static class Solution {
        public int majorityElement(int[] nums) {
            int res = nums[0];
            int count = 0;
            for (int i = 0; i < nums.length; i++) {
                if (res == nums[i]) {
                    count++;
                } else {
                    count--;
                }
                if (count == 0) {
                    res = nums[i + 1];
                }
            }
            return res;
        }
    }
    public static void main(String[] args) {
        Solution s = new Solution();
        int[] nums = {3,2,3};
        System.out.println(s.majorityElement(nums));
        int[] nums2 = {2,2,1,1,1,2,2};
        System.out.println(s.majorityElement(nums2));    }
}

public class reverseBetween {
    public static class ListNode {
        int val;
        ListNode next;
        ListNode(int x) { val = x; }
    }   
    public static ListNode createLinkedList(int[] nums) {
        if (nums == null || nums.length == 0) {
            return null;
        }
        ListNode head = new ListNode(nums[0]);
        ListNode cur = head;
        for (int i = 1; i < nums.length; i++) {
            cur.next = new ListNode(nums[i]);
            cur = cur.next;
        }
        return head;
    }
    public static void printLinkedList(ListNode head) {
        ListNode cur = head;
        while (cur != null) {
            System.out.print(cur.val + "->");
            cur = cur.next;
        }
        System.out.println("null");
    }
    public static class Solution {
        public ListNode reverseBetween(ListNode head, int left, int right) {
            if (left == 1) {
                return reverseN(head, right);
            }
            head.next = reverseBetween(head.next, left - 1, right - 1);
            return head;
        }
        ListNode successor = null; // 后驱节点
        // 反转以 head 为起点的 n 个节点，返回新的头结点
        ListNode reverseN(ListNode head, int n) {
            if (n == 1) {
                successor = head.next;
                return head;
            }
            ListNode last = reverseN(head.next, n - 1);
            head.next.next = head;
            head.next = successor;
            return last;
        }
    }
    public static void main(String[] args) {
        Solution s = new Solution();
        int[] nums = {1,2,3,4,5};
        ListNode head = createLinkedList(nums);
        printLinkedList(head);
        head = s.reverseBetween(head, 2, 4);
        printLinkedList(head);
        int[] nums2 = {5};
        head = createLinkedList(nums2);
        printLinkedList(head);
        head = s.reverseBetween(head, 1, 1);
        printLinkedList(head);
   }
}

import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
public class SplitTime {
    private static List<Date> dateSplit(Date startDate, Date endDate) throws Exception {
        if (!startDate.before(endDate))
            throw new Exception("开始时间应该在结束时间之后");
        Long spi = endDate.getTime() - startDate.getTime();
        Long step = spi / (24 * 60 * 60 * 1000);
        List<Date> dateList = new ArrayList<Date>();
        dateList.add(endDate);
        for (int i = 1; i <= step; i++) {
            dateList.add(new Date(dateList.get(i - 1).getTime() - (24 * 60 * 60 * 1000)));
        }
        return dateList;
    }
    public static void main(String[] args) throws ParseException {
        try {
            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
            Date start = sdf.parse("2015-4-20");
            Date end = sdf.parse("2015-5-2");
            List<Date> lists = dateSplit(start, end);
            if (!lists.isEmpty()) {
                for (Date date : lists) {
                    System.out.println(sdf.format(date));
                }
            }
        } catch (Exception e) {
        }
    }
}