Here is a solution in Python that uses just a single hash set and doesn't do any fancy interval merging.
def destruct_directed_run(num_set, start, direction):
while start in num_set:
num_set.remove(start)
start += direction
return start
def destruct_single_run(num_set):
arbitrary_member = iter(num_set).next()
bottom = destruct_directed_run(num_set, arbitrary_member, -1)
top = destruct_directed_run(num_set, arbitrary_member + 1, 1)
return range(bottom + 1, top)
def max_run(data_set):
nums = set(data_set)
best_run = []
while nums:
cur_run = destruct_single_run(nums)
if len(cur_run) > len(best_run):
best_run = cur_run
return best_run
def test_max_run(data_set, expected):
actual = max_run(data_set)
print data_set, actual, expected, 'Pass' if expected == actual else 'Fail'
print test_max_run([10,21,45,22,7,2,67,19,13,45,12,11,18,16,17,100,201,20,101], range(16, 23))
print test_max_run([1,2,3], range(1, 4))
print max_run([1,3,5]), 'any singleton output fine'
