Data commit

Task/Greatest-subsequential-sum/Ruby/greatest-subsequential-sum-1.rb

@@ -0,0 +1,10 @@
+def subarray_sum(arr)
+  max, slice = 0, []
+  arr.each_index do |i|
+    (i...arr.length).each do |j|
+      sum = arr[i..j].inject(0, :+)
+      max, slice = sum, arr[i..j]  if sum > max
+    end
+  end
+  [max, slice]
+end

Task/Greatest-subsequential-sum/Ruby/greatest-subsequential-sum-2.rb

@@ -0,0 +1,8 @@
+[ [1, 2, 3, 4, 5, -8, -9, -20, 40, 25, -5],
+  [-1, -2, 3, 5, 6, -2, -1, 4, -4, 2, -1],
+  [-1, -2, -3, -4, -5],
+  []
+].each do |input|
+  puts "\nInput seq: #{input}"
+  puts "  Max sum: %d\n   Subseq: %s" % subarray_sum(input)
+end

Task/Greatest-subsequential-sum/Ruby/greatest-subsequential-sum-3.rb

@@ -0,0 +1,22 @@
+# the trick is that at any point
+# in the iteration if starting a new chain is
+# better than your current score with this element
+# added to it, then do so.
+# the interesting part is proving the math behind it
+def subarray_sum(arr)
+  curr = max = 0
+  first, last, curr_first = arr.size, 0, 0
+  arr.each_with_index do |e,i|
+    curr += e
+    if e > curr
+      curr = e
+      curr_first = i
+    end
+    if curr > max
+      max = curr
+      first = curr_first
+      last = i
+    end
+  end
+  return max, arr[first..last]
+end