NOI '05 P2 - Maintaining a Sequence - DMOJ: Modern Online Judge

NOI '05 P2 - Maintaining a Sequence

View as PDF

Submit solution

All submissions

Best submissions

Points: 30 (partial)

Time limit: 0.6s

Memory limit: 64M

Problem type

National Olympiad in Informatics, China, 2005

Please write a program that maintains a sequence, supporting the following 6 operations:

Operation	Input Format	Description
1. Insert	`INSERT posi tot c₁ c₂ ... c_tot`	After the $posi$ ~posi~-th number in the current sequence, insert a total of $tot$ ~tot~ numbers: $c_1, c_2, \dots, c_{tot}$ ~c_1, c_2, \dots, c_{tot}~. Insertion to the beginning of the sequence will have $posi$ ~posi~ equal to 0.
2. Delete	`DELETE posi tot`	Starting at the $posi$ ~posi~-th number in the current sequence, delete a total of $tot$ ~tot~ consecutive numbers.
3. Modify	`MAKE-SAME posi tot c`	Starting at the $posi$ ~posi~-th number in the current sequence, change all the values of $tot$ ~tot~ consecutive numbers to $c$ ~c~.
4. Reverse	`REVERSE posi tot`	Starting at the $posi$ ~posi~-th number in the current sequence, reverse the order of $tot$ ~tot~ consecutive numbers.
5. Get Sum	`GET-SUM posi tot`	Starting at the $posi$ ~posi~-th number in the current sequence, output the sum of $tot$ ~tot~ consecutive numbers. Note that $tot = 0$ ~tot = 0~ is possible, in which case you should output $0$ ~0~.
6. Max Sum	`MAX-SUM`	Output the largest sum of any (non-empty) consecutive subsequence of the current sequence.

Input Specification

The first line of input contains two integers $N$ ~N~ and $M$ ~M~, where $N$ ~N~ is the initial length of the sequence and $M$ ~M~ is the number of operations.

The second line of input contains $N$ ~N~ integers, describing the initial sequence.

For the next $M$ ~M~ lines, each line contains a command in one of the formats described above.

Output Specification

For each GET-SUM or MAX-SUM operation in the input, output the result of the query on a separate line.

Sample Input

9 8
2 -6 3 5 1 -5 -3 6 3
GET-SUM 5 4
MAX-SUM
INSERT 8 3 -5 7 2
DELETE 12 1
MAKE-SAME 3 3 2
REVERSE 3 6
GET-SUM 5 4
MAX-SUM

Sample Output

Scoring

For each test case, your score will be determined as follows:

If your program prints the correct answers to all GET-SUM operations at the correct locations in the output, then you will score $60\%$ ~60\%~ of points.
If your program prints the correct answers to all MAX-SUM operations at the correct locations in the output, then you will score $40\%$ ~40\%~ of points.
If your program correctly answers both types operations, then you will score $100\%$ ~100\%~ of points.

Please note: If your program can only correctly process one type of operation, then ensure that operations of the other type each receive a corresponding line. Otherwise, we cannot guarantee that your score will be accurate.

Constraints

You may assume that at any given time, the sequence will contain at least 1 number.
The data in the input is guaranteed to be valid, and will always refer to existing positions in the sequence.

In test data worth at most $50\%$ ~50\%~ of the points, the sequence may contain up to $30\,000$ ~30\,000~ numbers at any given moment.
In test data worth $100\%$ ~100\%~ of the points, the sequence may contain up to $500\,000$ ~500\,000~ numbers at any given moment.

In test data worth $100\%$ ~100\%~ of the points, the value of any number in the sequence will be in the range $[-1\,000, 1\,000]$ ~[-1\,000, 1\,000]~.
In test data worth $100\%$ ~100\%~ of the points, $M \le 20\,000$ ~M \le 20\,000~, the sum of all inserted values will not exceed $4\,000\,000$ ~4\,000\,000~, and the input will not exceed 20MB.

Comments

0

AryanG commented on Jan. 2, 2020, 5:46 p.m. ← edited →

I am currently hitting a TLE on the 7th test case, is there any way to improve the algorithm?

1

wleung_bvg commented on Jan. 2, 2020, 7:10 p.m. ← edited →

Intended time complexity should be similar to $\mathcal{O}(M \log (N + M))$ ~\mathcal{O}(M \log (N + M))~. I recommend looking into data structures that can efficiently perform range updates and queries.