QOJ.ac

QOJ

Time Limit: 1 s Memory Limit: 256 MB Total points: 100

#2029. Minimum Cost Paths

Statistics

Farmer John's pasture can be regarded as an $N\times M$ ($2\le N\le 10^9$, $2\le M\le 2\cdot 10^5$) 2D grid of square "cells" (picture a huge chessboard). The cell at the $x$-th row from the top and $y$-th column from the right is denoted by $(x,y)$ for each $x\in [1,N], y\in [1,M]$. Furthermore, for each $y\in [1,M]$, the $y$-th column is associated with the cost $c_y$ ($1\le c_y\le 10^9$).

Bessie starts at the cell $(1,1)$. If she is currently located at the cell $(x,y)$, then she may perform one of the following actions:

  • If $y<M$, Bessie may move to the next column (increasing $y$ by one) for a cost of $x^2$.
  • If $x<N$, Bessie may move to the next row (increasing $x$ by one) for a cost of $c_y$.

Given $Q$ ($1\le Q\le 2\cdot 10^5$) independent queries each of the form $(x_i,y_i)$ ($x_i\in [1,N], y_i\in [1,M]$), compute the minimum possible total cost for Bessie to move from $(1,1)$ to $(x_i,y_i)$.

INPUT FORMAT (input arrives from the terminal / stdin):

The first line contains $N$ and $M$.

The second line contains $M$ space-separated integers $c_1,c_2,\ldots,c_M$.

The third line contains $Q$.

The last $Q$ lines each contain two space-separated integers $x_i$ and $y_i$.

OUTPUT FORMAT (print output to the terminal / stdout):

$Q$ lines, containing the answers for each query.

Note that the large size of integers involved in this problem may require the use of 64-bit integer data types (e.g., a "long long" in C/C++).

SAMPLE INPUT:

5 4
1 100 100 20
20
1 1
2 1
3 1
4 1
5 1
1 2
2 2
3 2
4 2
5 2
1 3
2 3
3 3
4 3
5 3
1 4
2 4
3 4
4 4
5 4

SAMPLE OUTPUT:

0
1
2
3
4
1
5
11
19
29
2
9
20
35
54
3
13
29
49
69
The output in grid format:
    1  2  3  4
  *--*--*--*--*
1 | 0| 1| 2| 3|
  *--*--*--*--*
2 | 1| 5| 9|13|
  *--*--*--*--*
3 | 2|11|20|29|
  *--*--*--*--*
4 | 3|19|35|49|
  *--*--*--*--*
5 | 4|29|54|69|
  *--*--*--*--*

SCORING:

  • Test cases 1-3 satisfy $N,M\le 2000$.
  • Test cases 4-8 satisfy $c_2>c_3>\cdots>c_M$.
  • Test cases 9-15 satisfy $N\le 2\cdot 10^5$.
  • Test cases 16-20 satisfy no additional constraints.

Problem credits: Benjamin Qi

Discussions

About Discussions

The discussion section is only for posting: Editorials, General Discussions (problem-solving strategies, alternative approaches), and Off-topic conversations.

This is NOT for reporting issues! If you want to report bugs or errors, please use the Issues section below.

Open Discussions 0
No discussions in this category.

Issues

About Issues

If you find any issues with the problem (statement, scoring, time/memory limits, test cases, etc.), you may submit an issue here. A problem moderator will review your issue.

Guidelines:

  1. This is not a place to publish discussions, editorials, or requests to debug your code. Issues are only visible to you and problem moderators.
  2. Do not submit duplicated issues. Submitting multiple issues may cause your account to be banned.
  3. Issues must be filed in English or Chinese only.
Active Issues 0
No issues in this category.
Closed/Resolved Issues 0
No issues in this category.