Question

Given is the following String:

String s = "Qba'g sbetrg gb qevax lbhe Binygvar";

My desired output is:

Don't forget to drink your ovaltine

My code:

public static String decrpyt(String s){

    String ans = "";

    for (int i = 0; i<s.length(); i++) {
        int x = s.charAt(i);

        if (x <= 105) {
            char c = ((char) (x + 13)); 
            ans += c;
        } else { 
            char c = ((char) (x - 13)); 
            ans += c;
        }
    }
    return ans;  
}

It returns:

don4t-forget-to-drink-_our-ovaltine

What do I need to do to get the desired output?

Answer 1

You are changing all characters, not just the letters, as has been mentioned in a comment. Carefully consider the range of characters that are letters that you need to modify. Declare x to be a char so that you don't have to consider the actual numeric ranges.

A-M => N-Z   Action: += 13
a-m => n-z   Action: += 13
N-Z => A-M   Action: -= 13
n-z => a-m   Action: -= 13
(all others) Action: No change

This can be expressed in 3 cases:

if ((x >= 'a' && x <= 'm') || (x >= 'A' && x <= 'M')) {
    // Add 13
} else if ((x >= 'n' && x <= 'z') || (x >= 'N' && x <= 'Z')){
    // Subtract 13
} else {
    // Use as is
}

Answer 2

You can add in an idea of exception characters. Basically any character in the exception list won't be translated. This would look something like:

public static String decrpyt(String s){

    String ans = "";

    for(int i = 0; i<s.length(); i++){
        // Could use a list or whatever, just giving you the idea here
        String characterAt = s.charAt(i).toString();
        if(characterAt.equals("'") || characterAt.equals(" "))
        {
            continue;
        }
        int x = s.charAt(i);

        if(x <= 105) {
            char c = ((char) (x + 13)); 
            ans += c;

        }

        else{ 
            char c = ((char) (x - 13)); 
            ans += c;
        }
    }
    return ans;  
}

How to decrypt this String

2 个答案: