Algorithm Problems

array_problems/arrays.rb

@@ -3,11 +3,48 @@
 
 module ArrayUtil
   def self.max(array)
+
+    # total_count = array.length
+    max_value = array[0]
+    counter = 0
+
+    # until counter == total_count do
+      array.each_index do |i|
+        if array[i] > max_value
+          max_value = array[i]
+        end
+      #   counter += 1
+      end
+    # end
+
+    return max_value
   end
 
   def self.middle_element(array)
+    #[3,2,1,4,5] = 1
+    #[3,2,1,2,4,5] = 1.5
+    if array.length == 0
+      return nil
+    end
+
+    # array_length = array.length
+    array_middle = array.length / 2 #middle for odd numbered arrays
+
+    if array.length.even?
+      average_val = (array[array_middle] + array[array_middle - 1]) / 2.0
+      return average_val
+    else
+      return array[array_middle]
+    end
   end
 
   def self.sum_arrays(array1, array2)
+    array3 = [ ]
+    array1.each_index do |i|
+      # array2.each_index do |i|
+        array3 << array1[i] + array2[i]
+      # end
+    end
+    return array3
   end
 end

set1/set1.rb

@@ -1,10 +1,55 @@
 module Set1
   def self.swap_small(array)
+    min_value = array[0]
+    min_value_index = 0
+
+    array.each_index do |i|
+      if array[i] < min_value
+        min_value = array[i]
+        min_value_index = i
+      end
+      array[min_value_index] = array[0]
+      array[0] = min_value
+    end
   end
 
   def self.find_sum_2(array, sum = 0)
+    if array.length == 0
+      return false
+    end
+
+    array.each_index do |i|
+      array.each_index do |x|
+        if array[i] + array[x] == 0
+          return true
+        elsif array[i] == 0 || array[x] == 0
+          return true
+        # else 
+          # return false
+        end
+      end
+    end
+    false
   end
 
   def self.find_sum_3(array)
+    if array.length == 0
+      return false
+    end
+
+    array.each_index do |i|
+      array.each_index do |x|
+        array.each_index do |r|
+          if array[i] + array[x] + array[r] == 0
+            return true
+          elsif array[i] == 0 || array[x] == 0 || array[r] == 0
+            return true
+          # else
+          #   return false 
+          end
+        end
+      end
+    end
+    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