blackout

Your mission

Merge two already sorted alarm streams into one sorted stream, deterministically.

today's brief

August 14, 2003. A control room in Ohio runs alarm software with a hidden race condition. Two processes reach for the same alarm queue at once, the alarm system stalls, and the operators stop seeing warnings just as power lines start to fail. Nobody reacts in time, and the cascade takes down the grid for 55 million people across the northeast US and Ontario, some of them for two days. The fix the racy code could never manage: merge the event streams in order, the same way every time. Do that.

See it in action

merge_alarms(out, {1,3,5}, 3, {2,4}, 2)

Expected result

1 2 3 4 5

Your checklist

For your own tracking. Tests grade your code.

a holds na timestamps in non-decreasing order. b holds nb timestamps in non-decreasing order.
Write all na + nb values into out in non-decreasing order.
Either input may be empty. When two values are equal, either one may come first, the result is the same.

More examples

merge_alarms(out, {2,2}, 2, {2}, 1)

Expected result

2 2 2

Constraints

Expected files

merge.c

Allowed functions

None. Write every helper yourself.

Back to compete

Solutions

blackout

Your mission

Merge two already sorted alarm streams into one sorted stream, deterministically.

today's brief

See it in action

merge_alarms(out, {1,3,5}, 3, {2,4}, 2)

Expected result

1 2 3 4 5

Your checklist

For your own tracking. Tests grade your code.

a holds na timestamps in non-decreasing order. b holds nb timestamps in non-decreasing order.
Write all na + nb values into out in non-decreasing order.
Either input may be empty. When two values are equal, either one may come first, the result is the same.

More examples

merge_alarms(out, {2,2}, 2, {2}, 1)

Expected result

2 2 2

Constraints

Expected files

merge.c

Allowed functions

None. Write every helper yourself.

Back to compete

Solutions