1.题目: 排序子序列

排序子序列https://www.nowcoder.com/questionTerminal/2d3f6ddd82da445d804c95db22dcc471?orderBy HotValue=1&page=1&onlyReference=false
【题目解析】：
本题要求解的是排序子序列，排序子序列为非递增或者非递减，很多同学在这个非递增、非递减问题上很纠结，注意：非递减就是a[i]<=a[i+1]，递减就是a[i]>a[i+1]，非递增就是a[i]>=a[i+1]，递增就是a[i]<a[i+1]。

import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * Description:排序子序列
 * User: YAO
 * Date: 2023-05-09
 * Time: 16:00
 */
public class work2 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int a = scanner.nextInt();
        int[] array = new int[a+1];
        for (int i = 0; i < a; i++) {
            array[i] = scanner.nextInt();
        }
        int i = 0;
        int count = 0;
        while (i < a){
            if (array[i] >array[i+1]){
                while (i < a && array[i] > array[i+1]){
                    i++;
                }
                i++;
                count++;
            }else if (array[i] == array[i+1]){
                i++;
            }else {
                while (i < a && array[i] < array[i+1]){
                    i++;
                }
                i++;
                count++;
            }
        }
        System.out.println(count);
    }
}

2. 题目: 倒置字符串

倒置字符串https://www.nowcoder.com/practice/ee5de2e7c45a46a090c1ced2fdc62355?tpId=85&&tqId=29867&rp =1&ru=/activity/oj&qru=/ta/2017test/question-ranking解题思路：
先将整个字符串逆置过来，再遍历字符串，找出每个单词，对单词逆置。

import java.util.*;
/**
 * Created with IntelliJ IDEA.
 * Description:将一句话的单词进行倒置，标点不倒置。比如 I like beijing. 经过函数后变为：beijing. like I
 * User: YAO
 * Date: 2023-05-09
 * Time: 15:07
 */
public class work1 {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        String str = scanner.nextLine();
        char[] ch = str.toCharArray();
        int len = ch.length;
        //逆置整个字符串
        reverse(ch,0,len-1);
        //逆置每个单独的单词
        int i = 0;
        while (i < len){
            int j = i;
            while (j < len && ch[j] != ' '){
                j++;
            }
            if (j < len){
                reverse(ch,i ,j-1);
                i = j + 1;
            }else {
                //此时逆置单词已经到了最后一个
                reverse(ch, i, j-1);
                i = j;
            }
        }
        // 将字符数组准转换为字符串
        String s = new String(ch);
        System.out.println(s);
    }
    public static void reverse(char[] arr, int start, int end){
        while (start <end){
            char tmp = arr[start];
            arr[start] = arr[end];
            arr[end] = tmp;
            start++;
            end--;
        }
    }
}