第2章 字符串和日期

1、字符串中A的数量

算法分析

直接模拟

时间复杂度

Java 代码

import java.util.Scanner;

public class Main{
    
    public static void main(String[] args) {
       Scanner scan = new Scanner(System.in);
       char[] charArray = scan.next().toCharArray();
       int res = 0;
       for(int i = 0;i < charArray.length;i ++)
           if(charArray[i] == 'A')
               res ++;
       System.out.println(res);
     }
}

2、最长的名字

算法分析

直接模拟

时间复杂度

Java 代码

import java.util.Scanner;

public class Main{
    static int N = 110;
    static String[] s = new String[N];
    public static void main(String[] args) {
       Scanner scan = new Scanner(System.in);
       int n = scan.nextInt();
       int res = 0;
       for(int i = 0;i < n;i ++)
       {
           s[i] = scan.next();
           res = Math.max(res, s[i].length());
       }
       for(int i = 0;i < n;i ++)
       {
           if(s[i].length() == res) System.out.println(s[i]);
       }
         
     }
}

3、字符串

算法分析

直接模拟

时间复杂度

Java 代码

import java.util.Scanner;

public class Main{
    static int N = 110;
    static String[] s = new String[N];
    public static void main(String[] args) {
       Scanner scan = new Scanner(System.in);
       char[] charArray = scan.next().toCharArray();
       String s = "";
       for(int i = 0;i < charArray.length;i ++)
       {
           char c ;
           if(charArray[i] - '0' >= 0 && charArray[i] - '0' <= 9) c = charArray[i];
           else if(charArray[i] == 'z') c = 'a'; 
           else if(charArray[i] == 'Z') c = 'A';
           else c = (char)((int)(charArray[i]) + 1);
           s += c;
       }
       System.out.println(s);
     }
}

4、大数的奇偶性判断

算法分析

判断最后一位

Java 代码

import java.util.Scanner;

public class Main{
    static int N = 110;
    static String[] s = new String[N];
    public static void main(String[] args) {
       Scanner scan = new Scanner(System.in);
       char[] charArray = scan.next().toCharArray();
       int len = charArray.length;
       if((charArray[len - 1] - '0') % 2 == 0) System.out.println("YES");
       else System.out.println("NO");
     }
}

5、字符反转

算法分析

直接翻转

Java代码

import java.util.Scanner;

public class Main{
    public static void main(String[] args) {
       Scanner scan = new Scanner(System.in);
       char[] charArray = scan.next().toCharArray();
       int len = charArray.length;
       for(int i = len - 1;i >= 0;i --)
           System.out.print(charArray[i]);
     }
}

6、最后一个单词