JAVA经典算法40题(4)

 【程序7】题目：输入一行字符，分别统计出其中英文字母、空格、数字和其它字符的个数。

程序分析：利用while语句,条件为输入的字符不为 '\n '.

import java.util.Scanner;
public class ex7 {
public static void main(String args[]){
System.out.println("请输入字符串：");
Scanner scan=new Scanner(System.in);
String str=scan.next();
String E1="[\u4e00-\u9fa5]";
Sintrting E2="[a-zA-Z]";
countH=0;
int countE=0;
char[] arrChar=str.toCharArray();
String[] arrStr=new String[arrChar.length];
for (int i=0;i
arrStr[i]=String.valueOf(arrChar[i]);
}
for (String i: arrStr ){
if (i.matches(E1)){
countH++;
}
if (i.matches(E2)){
countE++;
}
}
System.out.println("汉字的个数"+countH);
System.out.println("字母的个数"+countE);
}
}

import java.util.Scanner;
public class ex7 {
    public static void main(String args[]){
        System.out.println("请输入字符串：");
        Scanner scan=new Scanner(System.in);
        String str=scan.next();
        String E1="[\u4e00-\u9fa5]";
        Sintrting E2="[a-zA-Z]";
        countH=0;
        int countE=0;
        char[] arrChar=str.toCharArray();
        String[] arrStr=new String[arrChar.length];
        for (int i=0;i
            arrStr[i]=String.valueOf(arrChar[i]);
        }
        for (String i: arrStr ){
            if (i.matches(E1)){
                countH++;
            }
            if (i.matches(E2)){
                countE++;
            }
        }
        System.out.println("汉字的个数"+countH);
        System.out.println("字母的个数"+countE);
    }
}

 

【程序8】题目：求s=a+aa+aaa+aaaa+aa...a的值，其中a是一个数字。例如2+22+222+2222+22222(此时共有5个数相加)，几个数相加有键盘控制。

程序分析：关键是计算出每一项的值。

import java.io.*;
public class Sumloop {
public static void main(String[] args) throws IOException{
int s=0;
String output="";
BufferedReader stadin = new BufferedReader(new InputStreamReader(System.in));
System.out.println("请输入a的值");
String input =stadin.readLine();
for(int i =1;i<=Integer.parseInt(input);i++){
output += input;
int a = Integer.parseInt(output) ;
s+=a;
}
System.out.println(s);
}
}

import java.io.*;
public class Sumloop {
    public static void main(String[] args) throws IOException{
        int s=0;
        String output="";
        BufferedReader stadin = new BufferedReader(new InputStreamReader(System.in));
        System.out.println("请输入a的值");
        String input =stadin.readLine();
        for(int i =1;i<=Integer.parseInt(input);i++){
            output += input;
            int a = Integer.parseInt(output) ;
            s+=a;
        }
        System.out.println(s);
    }
}

另解:

import java.io.*;
public class Sumloop {
public static void main(String[] args) throws IOException{
int s=0;
int n;
int t=0;
BufferedReader stadin = new BufferedReader(new InputStreamReader(System.in));
String input = stadin.readLine();
n= Integer.parseInt(input);
for(int i=1;i<=n;i++){
t=t*10+n;
s=s+t;
System.out.println(t);
}
System.out.println(s);
}
}