fix performance test

Gemfile

@@ -5,3 +5,4 @@ source "https://rubygems.org"
 gem "rspec"
 gem "open3"
 gem "rubocop-shopify", require: false
+gem "descriptive_statistics"

Gemfile.lock

@@ -2,6 +2,7 @@ GEM
   remote: https://rubygems.org/
   specs:
     ast (2.4.2)
+    descriptive_statistics (2.5.1)
     diff-lcs (1.5.1)
     json (2.7.1)
     language_server-protocol (3.17.0.3)
@@ -50,6 +51,7 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
+  descriptive_statistics
   open3
   rspec
   rubocop-shopify

test/e2e/performance.rb

@@ -1,20 +1,19 @@
 # frozen_string_literal: true
 
 require_relative "helper/command_helper"
+require "descriptive_statistics"
 
 size = 500
+iters = 50
+
 results = []
 
-100.times do
+iters.times do
   input = (0...size).to_a.shuffle.map(&:to_s)
   stdout, _stderr, _status = execute_push_swap(*input)
   results << stdout.split("\n").count
 
   print "\e[32m.\e[0m"
 end
 
-max_operations = results.max
-min_operations = results.min
-average_operations = results.sum / results.size.to_f
-
-puts "\nFor size #{size}: Max: #{max_operations}, Min: #{min_operations}, Average: #{average_operations}"
+puts "\nFor size #{size}: Max: #{results.max}, Min: #{results.min}, Average: #{results.mean}, SD: #{results.standard_deviation.round(2)}" # rubocop:disable Layout/LineLength