find the mode of all keys in a map in ruby

To find the mode of all keys in a Map (or Hash in Ruby), we need to count the occurrences of each key and return the one with the highest frequency. We can do this by first counting the occurrences of each key using Enumerable#group_by and then finding the key with the highest frequency using Enumerable#max_by.

Here's an example implementation:

main.rb
map = { "a" => 1, "b" => 2, "c" => 2, "d" => 3 }

mode = map.group_by { |k, v| k }
           .max_by { |k, v| v.size }
           .first

puts mode #=> "b"
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In this example, we have a Map where key "b" and "c" have the same value of 2. We can find the mode of this Map using the code above, which will return the key "b" since it has the highest frequency of 2.