fix conflicts in merge

ruby/lib/array.rb

@@ -0,0 +1,2 @@
+class Array
+end

ruby/problem_001.rb

@@ -1,21 +1,29 @@
 #! /usr/bin/env ruby
 
-# http://projecteuler.net/problem=1
+# http://projecteuler.net/problem=9
 
-# If we list all the natural numbers below 10 that are multiples of 3 or 5, we get 3, 5, 6 and 9. The sum of these multiples is 23.
-# Find the sum of all the multiples of 3 or 5 below 1000.
+# A Pythagorean triplet is a set of three natural numbers, a  b  c, for which,
+
+# a^2 + b^2 = c^2
+
+# For example, 3^2 + 4^2 = 9 + 16 = 25 = 5^2.
+
+# There exists exactly one Pythagorean triplet for which a + b + c = 1000.
+# Find the product abc.
 
 require "benchmark"
 
 time = Benchmark.measure do
-  x = 0
-  i = 0
-  while i < 1000
-    if (i % 3 == 0) || (i % 5 == 0)
-      x += i
+
+  (1..1000).each do |a|
+    (1..1000).each do |b|
+      c = Math.sqrt(a**2 + b**2)
+      if (a + b + c == 1000) && (a < b)
+        puts (a * b * c).to_i
+      end
     end
-    i += 1
   end
+
 end
 
-puts time
+puts time

ruby/problem_010.rb

@@ -9,8 +9,24 @@
 require "benchmark"
 require_relative "lib/integer"
 
+def array_of_primes_for(val)
+  sieve = []
+  for i in 2 .. val
+    sieve[i] = i
+  end
+  for i in 2 .. Math.sqrt(val)
+    next unless sieve[i]
+    (i*i).step(val, i) do |j|
+      sieve[j] = nil
+    end
+  end
+  sieve.compact
+end
+
 time = Benchmark.measure do
-  2_000.sieve
+  primes = array_of_primes_for(2_000_000)
+  sum_of_primes = primes.inject {|sum, n| sum + n }
+  puts sum_of_primes
 end
 
 puts time

ruby/problem_011.rb

@@ -0,0 +1,94 @@
+#! /usr/bin/env ruby
+
+# In the 20x20 grid below, four numbers along a diagonal line have been marked in red.
+
+#  8  2 22 97 38 15  0 40  0 75  4  5  7 78 52 12 50 77 91  8
+# 49 49 99 40 17 81 18 57 60 87 17 40 98 43 69 48  4 56 62  0
+# 81 49 31 73 55 79 14 29 93 71 40 67 53 88 30  3 49 13 36 65
+# 52 70 95 23  4 60 11 42 69 24 68 56  1 32 56 71 37  2 36 91
+# 22 31 16 71 51 67 63 89 41 92 36 54 22 40 40 28 66 33 13 80
+# 24 47 32 60 99  3 45  2 44 75 33 53 78 36 84 20 35 17 12 50
+# 32 98 81 28 64 23 67 10 26 38 40 67 59 54 70 66 18 38 64 70
+# 67 26 20 68  2 62 12 20 95 63 94 39 63  8 40 91 66 49 94 21
+# 24 55 58  5 66 73 99 26 97 17 78 78 96 83 14 88 34 89 63 72
+# 21 36 23  9 75  0 76 44 20 45 35 14  0 61 33 97 34 31 33 95
+# 78 17 53 28 22 75 31 67 15 94  3 80  4 62 16 14  9 53 56 92
+# 16 39  5 42 96 35 31 47 55 58 88 24  0 17 54 24 36 29 85 57
+# 86 56  0 48 35 71 89  7  5 44 44 37 44 60 21 58 51 54 17 58
+# 19 80 81 68  5 94 47 69 28 73 92 13 86 52 17 77  4 89 55 40
+#  4 52  8 83 97 35 99 16  7 97 57 32 16 26 26 79 33 27 98 66
+# 88 36 68 87 57 62 20 72  3 46 33 67 46 55 12 32 63 93 53 69
+#  4 42 16 73 38 25 39 11 24 94 72 18  8 46 29 32 40 62 76 36
+# 20 69 36 41 72 30 23 88 34 62 99 69 82 67 59 85 74  4 36 16
+# 20 73 35 29 78 31 90  1 74 31 49 71 48 86 81 16 23 57  5 54
+#  1 70 54 71 83 51 54 69 16 92 33 48 61 43 52  1 89 19 67 48
+
+# The product of these numbers is 26  63  78  14 = 1788696.
+
+# What is the greatest product of four adjacent numbers in any direction (up, down, left, right, or diagonally) in the 20x20 grid?
+
+grid = [
+  [  8,  2, 22, 97, 38, 15,  0, 40,  0, 75,  4,  5,  7, 78, 52, 12, 50, 77, 91,  8 ],
+  [ 49, 49, 99, 40, 17, 81, 18, 57, 60, 87, 17, 40, 98, 43, 69, 48,  4, 56, 62,  0 ],
+  [ 81, 49, 31, 73, 55, 79, 14, 29, 93, 71, 40, 67, 53, 88, 30,  3, 49, 13, 36, 65 ],
+  [ 52, 70, 95, 23,  4, 60, 11, 42, 69, 24, 68, 56,  1, 32, 56, 71, 37,  2, 36, 91 ],
+  [ 22, 31, 16, 71, 51, 67, 63, 89, 41, 92, 36, 54, 22, 40, 40, 28, 66, 33, 13, 80 ],
+  [ 24, 47, 32, 60, 99,  3, 45,  2, 44, 75, 33, 53, 78, 36, 84, 20, 35, 17, 12, 50 ],
+  [ 32, 98, 81, 28, 64, 23, 67, 10, 26, 38, 40, 67, 59, 54, 70, 66, 18, 38, 64, 70 ],
+  [ 67, 26, 20, 68,  2, 62, 12, 20, 95, 63, 94, 39, 63,  8, 40, 91, 66, 49, 94, 21 ],
+  [ 24, 55, 58,  5, 66, 73, 99, 26, 97, 17, 78, 78, 96, 83, 14, 88, 34, 89, 63, 72 ],
+  [ 21, 36, 23,  9, 75,  0, 76, 44, 20, 45, 35, 14,  0, 61, 33, 97, 34, 31, 33, 95 ],
+  [ 78, 17, 53, 28, 22, 75, 31, 67, 15, 94,  3, 80,  4, 62, 16, 14,  9, 53, 56, 92 ],
+  [ 16, 39,  5, 42, 96, 35, 31, 47, 55, 58, 88, 24,  0, 17, 54, 24, 36, 29, 85, 57 ],
+  [ 86, 56,  0, 48, 35, 71, 89,  7,  5, 44, 44, 37, 44, 60, 21, 58, 51, 54, 17, 58 ],
+  [ 19, 80, 81, 68,  5, 94, 47, 69, 28, 73, 92, 13, 86, 52, 17, 77,  4, 89, 55, 40 ],
+  [  4, 52,  8, 83, 97, 35, 99, 16,  7, 97, 57, 32, 16, 26, 26, 79, 33, 27, 98, 66 ],
+  [ 88, 36, 68, 87, 57, 62, 20, 72,  3, 46, 33, 67, 46, 55, 12, 32, 63, 93, 53, 69 ],
+  [  4, 42, 16, 73, 38, 25, 39, 11, 24, 94, 72, 18,  8, 46, 29, 32, 40, 62, 76, 36 ],
+  [ 20, 69, 36, 41, 72, 30, 23, 88, 34, 62, 99, 69, 82, 67, 59, 85, 74,  4, 36, 16 ],
+  [ 20, 73, 35, 29, 78, 31, 90,  1, 74, 31, 49, 71, 48, 86, 81, 16, 23, 57,  5, 54 ],
+  [  1, 70, 54, 71, 83, 51, 54, 69, 16, 92, 33, 48, 61, 43, 52,  1, 89, 19, 67, 48 ]
+]
+
+def sum_for_array(array)
+  array.inject {|sum, n| sum + n }
+end
+
+def left_to_right_diagonals(grid)
+  diagonals = []
+
+  17.times do |hp|
+    17.times do |vp|
+      array = (0..3).collect { |i| grid[i + vp][i + hp] }
+      diagonals << array
+    end
+  end
+
+  diagonals
+end
+
+def right_to_left_diagonals(grid)
+  diagonals = []
+
+  17.times do |hp|
+    17.times do |vp|
+      array = (0..3).collect { |i| grid[i + vp][i + hp] }
+      diagonals << array
+    end
+  end
+
+  diagonals
+end
+
+
+array = (0..3).collect { |i| grid[i + 4][i] }
+
+# (0..3).collect { |i| grid[i][i] }
+
+
+
+
+
+
+
+