Common Interview Question: longest run of integers (implemented in coffeescript w/tests)

max_run.coffee

assert = (cond) ->
  throw("error") unless cond

max_run = (a) ->
  m = 0
  c = 0
  for n in a
    c += n
    c = 0 if c < 0
    m = c if m < c
  m


do () ->
  assert(max_run([]) == 0)
  assert(max_run([5]) == 5)
  assert(max_run([5, 2]) == 7)
  assert(max_run([5, 2, -3]) == 7)
  assert(max_run([5, 2, -3, 4]) == 8)
  assert(max_run([5, 2, -3, 4, -2]) == 8)
  assert(max_run([5, 2, -3, 4, -2, 3]) == 9)
  assert(max_run([5, 2, -3, 4, -2, 3, -15]) == 9)
  assert(max_run([-1000, 5, 2, -3, 4, -2, 3, -15]) == 9)
  assert(max_run([2, -1000, 5, 2, -3, 4, -2, 3, -15]) == 9)
  assert(max_run([43, -1000, 5, 2, -3, 4, -2, 3, -15]) == 43)
  assert(max_run([1001, -1000, 5, 2, -3, 4, -2, 3, -15]) == 1001)
  assert(max_run([3, -1000, 4])  == 4)
  assert(max_run([500, -1000, 4])  == 500)
  assert(max_run([1001, -1000, 4])  == 1001)
  assert(max_run([1001, -1, 4])  == 1004)
  assert(max_run([-10, 2, 3, -2, 5, -15]) == 8)