Question

I want to know how to generate all words using java from specified characters and length

String first[]={"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};
String second[]={"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};
String ch ="";  
String total[];

for(int i = 0;i<26;i++) {
    for(int j = 0;j<26;j++) {
        ch+=first[i]+first[j];
        System.out.println(ch);
    }
}

I get only 576 words only by this program, but the 26! words is 4.03291461 × 10^26

How to write the program in java?

Answer 1

Here’s my solution. It’s kind of quick, so don’t be too hard on the optimization.

public static void printWords(int length) {

    if (length < 1)
        throw new IllegalArgumentException();

    printWordsRec("", length);
}

private static void printWordsRec(String base, int length) {

    for (char c = 'a'; c <= 'z'; c++) {
        if (length == 1) {
            System.out.println(base + c);
        }
        else {
            printWordsRec(base + c, length - 1);
        }
    }
}