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Anagrams

ISC 2005 Computer Science Practical, Question 3 · Strings, Recursion

The question

We would like to generate all possible anagrams of a word. For example if the given word is ‘TOP’, there will be 6 possible anagrams:

TOP
TPO
OTP
OPT
POT
PTO

An anagram must be printed only once. You may output the anagrams in any order.

Also, output the total number of anagrams.

You may assume that the number of letters, N, in the word will be 7 at most, i.e. N < 7

Test your program for the given data and some random data.

SAMPLE DATA:

INPUT:
TO
OUTPUT:
TO
OT
Total number of anagrams=2

INPUT:
LEAN
OUTPUT:
LEAN
LENA
LAEN
LANE
LNAE
LNEA
ELAN
ELNA
EALN
EANL
ENAL
ENLA
AELN
AENL
ALEN
ALNE
ANLE
ANEL
NEAL
NELA
NAEL
NALE
NLAE
NLEA
Total number of anagrams = 24

Question: ISC 2005 Computer Science Paper 2 (Practical), Question 3, set by the Council for the Indian School Certificate Examinations (CISCE). Solution and video: Vinay Singh.

Java solution

ISC2005Q3.java Download GitHub

import java.util.*;

class Anagram {
    private String word, output;
    private int count;

    public Anagram(String word) {
        this.word = word;
        char s[] = word.toCharArray();
        output = "";
        count = 0;
        permute(s, 0);
    }

    public void permute(char s[], int k) {
        if (k == s.length - 1) {
            output += new String(s) + "\n";
            count++;
        } else {
            char temp;
            for (int i = k; i < s.length; i++) {
                if (s[i] == s[k] && i != k)
                    continue;
                temp = s[k];
                s[k] = s[i];
                s[i] = temp;
                permute(s, k + 1);
                temp = s[k];
                s[k] = s[i];
                s[i] = temp;
            }
        }
    }

    public String toString() {
        return output;
    }

    public int length() {
        return count;
    }
}

class ISC2012Q1 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        System.out.println("INPUT:");
        String word = in.next();
        Anagram obj = new Anagram(word);
        System.out.println("OUTPUT:\n" + obj);
        System.out.println("Total number of anagrams=" + obj.length());
        in.close();
    }
}

Anagrams

The question

Java solution

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