如果检查用户输入字符串的语句是否包含用户输入的字母，不包括任何额外字母

Question

I need to create a program in which a string and 5 letters are entered by the user and the program checks if the string can be created again from those 5 letters, but ignores any letters that the string cannot be created from.

For example, if I enter the word "hello" and then I enter the 5 letters "h", "e", "l", "o", and "p", I want the program to makes sure that those letters do make up the word "hello", but ignores any extra letters, which in this case is the "p". Another example, if I enter the word "apple" and then I enter the 5 letters "a", "p", "l", "o", and "f", I want the program to recognize that those letters do not create the word apple and to ignore the letters "o" and "f".

If the program does verify that the string can be created from those 5 letters, while ignoring any extras, then it will output "You win!", but if not it will output "You lose!". Here is the code I have so far:

public static void main(String[] args) {

    Scanner keyboard = new Scanner (System.in);
    System.out.print("Please enter a word: ");
    String in = keyboard.nextLine();
    System.out.print("Please enter the first letter: ");
    String letter1 = keyboard.next();
    System.out.print("Please enter the second letter: ");
    String letter2 = keyboard.next();
    System.out.print("Please enter the third letter: ");
    String letter3 = keyboard.next();
    System.out.print("Please enter the fourth letter: ");
    String letter4 = keyboard.next();
    System.out.print("Please enter the fifth letter: ");
    String letter5 = keyboard.next();

    if (in.contains(letter1 + letter2 + letter3 + letter4 + letter5)) {
        System.out.println("You win!");
    } else {
        System.out.println("You lose!");
    }

}

Here is the output I am getting when I run this:

I am new to Java so I do not know if there is some kind of code I could use to do this. If somebody does know, please lead me in the right direction.

Answer 1

The easiest algorithm I can think of is: For each character inputted, remove all occurences from the string. At the end, check if string is empty. Or in code:

char[] cs = new char[] {'h', 'e', 'l', 'o', 'p'};
String s = "hello";
for (char c : cs) s = s.replace(c+"", "");
if (s.isEmpty()) System.out.println("You win!");

Note that this approach is not performing very well. For a given number of characters n and a string length m this performs as O(n*m) . It also does a lot of costly String reallocations.

Answer 2

The statement letter1 + letter2 + letter3 + letter4 + letter5 concatenates the strings. If you stored the results of it in a variable then that variable would be equal to the string helop .

I would store letters 1-5 in some kind of Collection and then check each character to see if it is in that collection using charAt . There are other more efficient ways of solving your problem but I think this is the most clear.