Chantal's Big-O answered problems

efficiency.rb

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+
+# 1)
+
+def largest?(array, value)
+  array.each do |item|
+    return false if item > value
+  end
+  return true
+end
+
+# This is O(n) because the data grows proportionately along with the loop.
+
+# 2)
+
+def info_dump(customers)
+  puts "Customer Names: "
+  customers.each do |customer|
+    puts "#{customer[:name]}"
+  end
+  puts "Customer Locations: "
+  customers.each do |customer|
+    puts "#{customer[:country]}"
+  end
+end
+
+# This is O(n) because the loops aren't nested, and they will run a certain number of times.
+
+# 3)
+
+def first_element_is_red?(array)
+  array[0] == 'red' ? true : false
+end
+
+# this is constant, O(1) because we must only check the first element of the array and put it.
+
+# 4)
+def duplicates?(array)
+  array.each_with_index do |item1, index1|
+    array.each_with_index do |item2, index2|
+      next if index1 == index2
+      return true if item1 == item2
+    end
+  end
+  false
+end
+
+# This is quadratic, O(n^2) because there are nested loops.
+
+# 5)
+
+words = [chocolate, coconut, rainbow]
+endings = [cookie, pie, waffle]
+
+words.each do |word|
+  endings.each do |ending|
+    puts word + ending
+  end
+end
+
+# This is O(n * m) because though the loops are nested, they are independent and run linearly.
+
+# 6)
+numbers = # some array (you don't know contents)
+
+def print_array(array)
+    array.each {|num| puts num}
+end
+
+# This is linear, O(n) because the data grows proportionately along with the loop.
+
+# 7)
+
+# this is insertion sort
+(2...num.length).each do |j|
+    key = num[j]
+    i = j - 1
+    while i > 0 and num[i] > key
+        num[i+1] = num[i]
+        i = i - 1
+    end
+    num[i+1] = key
+end
+
+# This is quadratic because as we get more elements, things get exponentially more expensive.
+
+# 8)
+
+# this is selection sort
+n.times do |i|
+  index_min = i
+  (i + 1).upto(n-1) do |j|
+    index_min = j if a[j] < a[index_min]
+  end
+  a[i], a[index_min] = a[index_min], a[i] if index_min != i
+end
+
+# This is quadratic because the data grows proportionately along with the loops.