49. Leetcode group anagrams problem with 3 approaches

leetcode_49_group_anagrams_with_3_solution.rb

=begin

Leetcode 49. Group Anagrams
Given an array of strings strs, group the 
anagrams
 together. You can return the answer in any order.

Example 1:

Input: strs = ["eat","tea","tan","ate","nat","bat"]

Output: [["bat"],["nat","tan"],["ate","eat","tea"]]

Explanation:

There is no string in strs that can be rearranged to form "bat".
The strings "nat" and "tan" are anagrams as they can be rearranged to form each other.
The strings "ate", "eat", and "tea" are anagrams as they can be rearranged to form each other.
Example 2:

Input: strs = [""]

Output: [[""]]

Example 3:

Input: strs = ["a"]

Output: [["a"]]

=end

# @param {String[]} strs
# @return {String[][]}

## Approach with 2D matrix with 26 alphabet approach
def group_anagrams(strs)
    ascii_str_a = 97
    mtrx = Array.new(strs.length) { Array.new(26) {0}}
    strs.each_with_index do |st, i|
        st.split('').each do |ch|
            j = ch.ord - ascii_str_a
            mtrx[i][j] += 1
        end
    end
    # Initialize a hash to group anagrams
    anagram_groups = Hash.new { |hash, key| hash[key] = [] }

    # Go through the matrix and group the rows that are identical
    mtrx.each_with_index do |row, i|
        anagram_groups[row] << i
    end

    anagram_groups.values.map{|x| temp_a = []; x.each{|i| temp_a << strs[i]}; temp_a }
end


def group_anagrams(strs)
    sum_ascii_hash = {}
    strs.each_with_index do |str, i|
        sorted_aa = str.chars.sort.join
        sum_ascii_hash["#{sorted_aa}"] ? sum_ascii_hash["#{sorted_aa}"] << i : sum_ascii_hash["#{sorted_aa}"] = [i]
    end
    sum_ascii_hash.values.map{|ind_arr| ind_arr.map{|ind| strs[ind]}}
end

# Partially correct approach by calculating ascii value
def old_group_anagrams(strs)
    sum_ascii_hash = {}
    strs.each_with_index do |str, i|
        sum_key = str.split("").uniq.sum { |char| char.ord }
        Ignore: #sum_key = str.split("").sum { |char| char.ord }
        Ignore: #sum_key = str.split("").each_with_index.map{|char, i| char.ord * i}.sum
        sum_ascii_hash["#{sum_key}"] ? sum_ascii_hash["#{sum_key}"] << i : sum_ascii_hash["#{sum_key}"] = [i]
    end
    sum_ascii_hash.values.map{|ind_arr| ind_arr.map{|ind| strs[ind]}}
end