find the sum of all keys in a map in ruby

To find the sum of all keys in a Ruby hash, you can use the inject method to iterate through the hash and accumulate the sum of all keys. Here's an example code snippet:

main.rb
my_hash = {a: 1, b: 2, c: 3}
sum_of_keys = my_hash.keys.inject(0) { |sum, key| sum + key }
puts sum_of_keys # output: 6
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In this example, we first define a hash named my_hash with some key-value pairs. We then call the keys method on the hash to get an array of its keys. We then call inject on this array with an initial value of 0 for the sum.

The block passed to inject takes in two arguments: sum and key. In each iteration, sum is updated to be the current value of sum plus the current key.

After all iterations are complete, inject returns the final value of the accumulator, which in this case is the sum of all keys. We then print this sum to the console using puts.