Thursday, August 21, 2014

Print all permutation of given string in Java


Program:


Note: We can use Set data structure to avoid repeated elements.

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1 comment:

  1. manojAugust 21, 2014 at 5:50 AM


    public static ArrayList allPermutations(String str) {
    if (str == null)
    return null;

    ArrayList list = new ArrayList();

    if (str.length() == 0) {
    list.add("");
    return list;
    }

    char first = str.charAt(0);

    String remaining = str.substring(1);

    ArrayList words = allPermutations(remaining);
    for (String word : words) {
    for (int i = 0; i <= word.length(); i++) {
    String s = insertAt(word, i, first);

    list.add(s);
    }
    }
    return list;
    }

    private static String insertAt(String s, int index, char ch) {
    if (index < 0 || index > s.length())
    throw new IllegalArgumentException("Index out of bound.");
    String s1 = s.substring(0, index);
    String s2 = s.substring(index);
    return s1 + ch + s2;
    }

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