Order book Yuriy Lyfenko

Simulate a sell-side order book and calculate the cost of a final purchase as fast as possible.

Input

1,000,000 order updates on STDIN, one per line:

  • + <price> <size> – add a new sell order
  • - <position> – delete the order at the given position
  • = <size> – buy <size> shares from the top of the order book

After all updates are processed, buy 1,000 shares from the top of the order book.

Output

Print the total cost of the final 1,000-share purchase to STDOUT.

Order Book Rules

Orders are sorted by price ascending (lower is better). Orders at the same price are sorted by arrival time (earlier first). Position 0 is the best (lowest-price) offer.

The = (buy) operation consumes shares starting from position 0. If an order is fully consumed, it is removed from the book.

Example

Input Order book state
+ 1137 100 (1137,100)
+ 1130 10 (1130,10), (1137,100)
+ 1130 50 (1130,10), (1130,50), (1137,100)
- 0 (1130,50), (1137,100)
+ 1150 200 (1130,50), (1137,100), (1150,200)
= 200 (1150,150)

Total cost of the last buy: 50 * 1130 + 100 * 1137 + 50 * 1150.

Back to listNov 29, 2023 03:16yenw0dyenw0dError
Source Code

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Challenge History
DateChallengerCostTypeStatus
Sep 11, 2026 14:03Andrew Epstein10.00CustomSolution Broken
Run Statistics
#DateScoreWall TimeCPU UserCPU SystemMemoryError
1Sep 11, 2026 14:07012,865,6561,481,000045,056Exit with code 2: panic: price level index out of bounds: 21979 goroutine 1 [running]: main.(*ArrayBookSide).Insert(0x7b18b6400000?, 0xc000056e98?, 0x476e46?) /src/arraybacked.go:72 +0x179 main.OrderBookMain({0x7b18b6400000, 0xd6c388, 0xd6c388}, {0x4...stderr
2Nov 29, 2023 03:16135,638107,546,14376,653,0002,017,0002,322,432
3Nov 29, 2023 03:16137,707113,066,47876,875,0002,995,0002,531,328
4Nov 29, 2023 03:16138,116107,696,23679,106,0001,001,0002,338,816
5Nov 29, 2023 03:16139,469109,393,38476,898,0003,994,0002,342,912
6Nov 29, 2023 03:16145,169118,245,70282,194,0002,004,0002,478,080
7Nov 29, 2023 03:16145,481108,484,64381,366,0003,013,0002,441,216
8Nov 29, 2023 03:16146,750112,872,16782,111,0003,004,0002,531,328
9Nov 29, 2023 03:16153,322118,103,41486,929,0001,998,0002,383,872
10Nov 29, 2023 03:16156,643122,871,03787,858,0002,995,0002,314,240
11Nov 29, 2023 03:16163,909176,217,61495,067,34302,306,048
12Nov 29, 2023 03:16163,970150,826,75095,102,73702,199,552
13Nov 29, 2023 03:16164,128162,444,83995,194,19502,260,992