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 listDec 24, 2025 02:43RussellStrongRussellStrongError
Source Code

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Challenge History
DateChallengerCostTypeStatus
Sep 11, 2026 14:14Andrew Epstein10.00CustomSolution Broken
Run Statistics
#DateScoreWall TimeCPU UserCPU SystemMemoryError
1Sep 11, 2026 14:20010,785,207921,000028,672Exit with code 101: thread 'main' (1) panicked at main.rs:132:34: explicit panic note: run with `RUST_BACKTRACE=1` environment variable to display a backtracestderr
2Dec 24, 2025 02:43137,850108,806,67776,955,0002,998,0002,289,664
3Dec 24, 2025 02:43139,424105,645,33677,871,0002,995,0002,351,104
4Dec 24, 2025 02:43139,484111,419,36978,904,0001,997,0002,289,664
5Dec 24, 2025 02:43139,576110,921,77377,956,0002,998,0002,289,664
6Dec 24, 2025 02:43139,686103,440,38179,018,0002,000,0002,351,104
7Dec 24, 2025 02:43139,891109,067,18478,132,0003,005,0002,347,008
8Dec 24, 2025 02:43140,738110,594,81879,613,0002,015,0002,342,912
9Dec 24, 2025 02:43140,747102,376,49079,618,0002,015,0002,289,664
10Dec 24, 2025 02:43141,167109,356,99480,879,000998,0002,347,008