Algorithm for grouping anagram words

Question

Given a set of words, we need to find the anagram words and display each category alone using the best algorithm.

input:

man car kile arc none like
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Answer 1

I wouldn't use hashing since it adds additional complexity for look-up and adds. Hashing, sorting and multiplications are all going to be slower than a simple array-based histogram solution with tracking uniques. Worst case is O(2n):

// structured for clarity
static bool isAnagram(String s1, String s2)
{
    int[] histogram = new int[256];

    int uniques = 0;

    // scan first string
    foreach (int c in s1)
    {
        // count occurrence
        int count = ++histogram[c];

        // count uniques
        if (count == 1)
        {
            ++uniques;
        }
    }

    // scan second string
    foreach (int c in s2)
    {
        // reverse count occurrence
        int count = --histogram[c];

        // reverse count uniques
        if (count == 0)
        {
            --uniques;
        }
        else if (count < 0) // trivial reject of longer strings or more occurrences
        {
            return false;
        }
    }

    // final histogram unique count should be 0
    return (uniques == 0);
}