did 38

SamGerber · SamGerber · commit 20d437bfeac2 · 2015-10-04T22:45:47.000Z
diff --git a/project-euler/38-integer_right_triangles.rb b/project-euler/38-integer_right_triangles.rb
@@ -0,0 +1,49 @@
+# Integer right triangles
+# Problem 39
+# If p is the perimeter of a right angle triangle with integral 
+# length sides, {a,b,c}, there are exactly three solutions for p = 120.
+
+# {20,48,52}, {24,45,51}, {30,40,50}
+
+# For which value of p ≤ 1000, is the number of solutions maximised?
+
+# Solution by Sam Gerber
+
+
+
+
+# This method returns an array of pythagorean triples whose sum does not
+# exceed max_perimeter
+
+
+def pythagorean_triples(max_perimeter)
+  triples = {}
+  # a = b = c = 0
+
+  (1...max_perimeter).each do |a|
+    (a + 1 ...max_perimeter).each do |b|
+      c = Math.sqrt(a**2 + b**2)
+      if c % 1 == 0
+        c = c.to_i
+        perimeter = a + b + c
+        if triples[perimeter] == nil && perimeter < max_perimeter
+          triples[perimeter] = [[a, b, c]]
+        elsif perimeter < max_perimeter
+          triples[perimeter] << [a, b, c]
+        end
+      end
+    end
+  end
+  triples
+end
+
+hash = pythagorean_triples(1_000)
+best = [0, 0]
+hash.each do |perimeter, triples|
+  if triples.count > best[1]
+    best = [perimeter, triples.count]
+  end
+end
+puts best
+puts ""
+print hash[best[0]]
