字符串中的子字

Question

null

Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
ArrayList<String> s = new ArrayList();
for (int i = 0; i <= n; i++)
{
    String st = sc.nextLine();
    s.add(st);
}

int q = sc.nextInt();

for (int i = 0; i<q;i++)
{
    int count = 0;
    String st = sc.nextLine();
    String check = "\\w"+st+"\\w";
    Pattern p = Pattern.compile(check);
    for (int j = 0; j < n; j++)
    {
       Matcher m = p.matcher(s.get(j));
       while (m.find())
       {
           count += 1;
       }
   }

   System.out.println(count);
}

有人能帮我弄清楚为什么上面的代码给出了错误的答案吗？

Answer 1

这里要提两件事：

• 对nextint()的调用不使用换行符，您必须显式调用nextline()或抓取整行并转换为int（此处对此进行解释）
• regex将不匹配模式的连续出现（就像ISIS中的两个is)，您需要将\\\w替换为\\b（非单词边界）。

请参见一个固定的代码片段：

Scanner sc = new Scanner(System.in);
int n = sc.nextInt();
sc.nextLine(); // Force it to consume the line break
ArrayList<String> s = new ArrayList();
for (int i = 0; i < n; i++)
{
    String st = sc.nextLine();
    s.add(st);
}

int q = sc.nextInt();
sc.nextLine(); // Force it to consume the line break
for (int i = 0; i < q; i++)
{
    int count = 0;
    String st = sc.nextLine();
    String check = "\\B" + st + "\\B";
    Pattern p = Pattern.compile(check);
    for (int j = 0; j < n; j++)
    {
       Matcher m = p.matcher(s.get(j));
       while (m.find())
       {
           count += 1;
       }
   }
   System.out.println(count); // => 3
}