Hashmap 代码未通过所有测试用例

Question

I was trying to solve a question for Java Hashmaps where we need to search if key is present or not. If yes, print the String value otherwise print -1.

public static void main(String args[] ) throws Exception {
        /* Enter your code here. Read input from STDIN. Print output to STDOUT */
        Map<Integer,String> hmap=new HashMap<Integer,String>();
        Scanner in=new Scanner(System.in);
        int length= in.nextInt();
        
        for(int i=0;i<length;i++) {
            hmap.put(in.nextInt(),in.nextLine());
        }
        while(in.hasNext()) {
            int number= in.nextInt();
            if(hmap.containsKey(number)) {
                String value=hmap.get(number);
                System.out.println(value);
            }
            else {
                System.out.println(-1);
            }
        }
        in.close();
    }

But all test cases are not passing. Can anyone please help with what is wrong?

Answer 1

Scanner has a problem interpreting your input if you use in.nextLine() after in.nextInt(). It is because the newline (\\n) of your int input (eg 4 ENTER => 4\\n) remains after returning the int via in.nextInt() and is recognized by the in.nextLine(). As workaround you could use an additional in.nextLine().

    for(int i=0;i<length;i++) {
        Integer key =in.nextInt();
        in.nextLine();
        String line = in.nextLine ();
        hmap.put(key,line);
    }