Arrays

array_problems/arrays.rb

@@ -2,12 +2,64 @@
 require 'pry-byebug'
 
 module ArrayUtil
+
+
+
   def self.max(array)
+
+  	x = array[0]
+
+  	array.each_with_index do |item, index| 
+  		if (array[index] > x)
+        x = array[index]
+      end
+  	end
+
+    x
+
   end
 
+
+
+
+
+
+
+
   def self.middle_element(array)
+
+    mid_index_neg_length = array.length / 2
+    mid_neg_value = array[mid_index_neg_length]
+
+    if array.empty?
+      nil
+    elsif array.length.odd?
+      mid_neg_value
+    else
+      (mid_neg_value + array[(mid_index_neg_length-1)]) / 2.0
+    end
+
   end
 
+
+
+
+
+
+
+
+
+
   def self.sum_arrays(array1, array2)
+
+    array3 = []
+
+    array1.each_with_index do |x,y|
+      array3 << (x + array2[y])
+    end
+
+    array3
+
   end
+
 end

set1/set1.rb

@@ -1,10 +1,52 @@
 module Set1
+
+	#O(n)
   def self.swap_small(array)
-  end
+  	first_element=array[0]
+
+  	smallest_value = array[0]
+  	smallest_index = 0
 
+  	array.each_with_index do |item, index|
+  		if array[index] < smallest_value
+  			smallest_value = array[index]
+  			smallest_index = index
+  		end
+  	end
+
+  	array.insert(0, smallest_value)
+  	array.delete_at(1)
+  	array.delete_at(smallest_index)
+  	array.insert(smallest_index, first_element)
+  end
+  #O(n^2)
   def self.find_sum_2(array, sum = 0)
+
+
+  	array.each do |x| 
+  		 array.each do |a|
+  		 	if x + a == 0
+  		 		return true
+  		 	end
+  		end
+  	end
+
+  	return false
+
   end
 
+  #O(n^3)
   def self.find_sum_3(array)
+  	array.each do |a|
+  		array.each do |b|
+  			array.each do |c|
+  				if a + b + c == 0
+  					return true
+  				end
+  			end
+  		end
+  	end
+
+  	return false
   end
 end

set1/spec/set1_spec.rb

@@ -24,48 +24,48 @@
   end
 
   describe ".find_sum_2" do
-    xit "should return false for an empty array" do
+    it "should return false for an empty array" do
       expect(Set1.find_sum_2([])).to eq(false)
     end
 
-    xit "should return true for an array with just the number 0" do
+    it "should return true for an array with just the number 0" do
       expect(Set1.find_sum_2([0])).to eq(true)
     end
 
-    xit "should return true for an array with the number 0 in it" do
+    it "should return true for an array with the number 0 in it" do
       expect(Set1.find_sum_2([5, 2, 0, -100])).to eq(true)
     end
 
-    xit "should return true if a number and it's negative are in the arrray" do
+    it "should return true if a number and it's negative are in the arrray" do
       expect(Set1.find_sum_2([5, 20, -5, 100])).to eq(true)
       expect(Set1.find_sum_2([5, 20, -3, 100, -20, 2])).to eq(true)
     end
 
-    xit "should return false if none of the numbers add to 0" do
+    it "should return false if none of the numbers add to 0" do
       expect(Set1.find_sum_2([5, 6, 7, 8, -1, -2, -3, -4])).to eq(false)
     end
   end
 
   describe ".find_sum_3" do
-    xit "should return false for an empty array" do
+    it "should return false for an empty array" do
       expect(Set1.find_sum_3([])).to eq(false)
     end
 
-    xit "should return true for an array with just the number 0" do
+    it "should return true for an array with just the number 0" do
       expect(Set1.find_sum_3([0])).to eq(true)
     end
 
-    xit "should return true for an array with the number 0 in it" do
+    it "should return true for an array with the number 0 in it" do
       expect(Set1.find_sum_3([5, 2, 0, -100])).to eq(true)
     end
 
-    xit "should return true if 3 numbers in the array add to 0" do
+    it "should return true if 3 numbers in the array add to 0" do
       expect(Set1.find_sum_3([10, 2, 100, -200, -102, 5])).to eq(true)
       expect(Set1.find_sum_3([10, -51, 100, -201, 102, 5])).to eq(true)
       expect(Set1.find_sum_3([10, 51, 100, -201, -102, 5])).to eq(true) # 51, 51, -102
     end
 
-    xit "should return false if no 3 numbers in the array add to 0" do
+    it "should return false if no 3 numbers in the array add to 0" do
       expect(Set1.find_sum_3([10, 51, 100, 201, 102, 5])).to eq(false)
     end
   end