用于判断字符串是否为Pangram的代码？

Question

import java.io.*;
import java.util.*;


public class Solution {

    public static final int n = 26; 

    public int check(String arr) {
        if (arr.length() < n) {
           return -1;
        }
        for (char c = 'A'; c <= 'Z'; c++) {
            if ((arr.indexOf(c) < 0) && (arr.indexOf((char)(c + 32)) < 0)) {
               return -1;
            }
        }
        return 1;
    }  
}

public static void main(String[] args) {
    Scanner s1 = new Scanner(System.in);
    String s = s1.next();
    Solution obj = new Solution();

    int d = obj.check(s);

    if (d == -1) {
        System.out.print("not pangram");
    } else {
        System.out.print("pangram");
    }
}

如果输入的字符串是:
我们立即判断下一个奖项的古董象牙扣

它会给出错误的输出:
不是pangram.

我无法找出代码有什么问题.
提前致谢!

Answer 1

问题是whitespace是一个分隔符Scanner.next().因此,当您输入时We promptly judged antique ivory buckles for the next prize,s将指向字符串We.当你打电话obj.check(s)时We它会返回-1.

要验证是否是这种情况,您可以打印s并检查其值.你也可以这样做:

String s = "We promptly judged antique ivory buckles for the next prize";

打电话obj.check(s),看看它会返回正确的答案.

要修复它,你应该调用Scanner.nextLine()而不是Scanner.next():

String s = s1.nextLine();

Answer 2

May be program by using set will make solution easier ..:)


import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.util.HashSet;
import java.util.Set;

public class Pangram {

public static void main(String args[]) {

    try {
        final String str;
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        str = br.readLine().toLowerCase().replaceAll(" ", "");

        char[] chars = str.toCharArray();
        final Set set = new HashSet();

        for(char c: chars){
            set.add(c);
        }

        System.out.println(set.size());
        if(set.size() == 26)
           System.out.println("pangram");
        else
            System.out.println("not pangram");

    } catch (Exception e) {
        e.printStackTrace();
    }

}

}

Answer 3

另一个版本:

import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {

        Scanner scan = new Scanner(System.in);
        String sentence = scan.nextLine();
        sentence = sentence.toUpperCase();
        sentence = sentence.replaceAll("[^A-Z]", "");

        char[] chars = sentence.toCharArray();

        Set<Character> set = new HashSet<Character>();

        for( int i = 0; i < chars.length; i++ ) set.add(chars[i]);

        System.out.println(set.size() == 26 ? "pangram" : "not pangram");

    }
}