Codeforces Round 802 (Div. 2)
A
Optimal Path
Codeforces
800
原题
←B →
翻译中…

You are given a table $a$ of size $n \times m$. We will consider the table rows numbered from top to bottom from $1$ to $n$, and the columns numbered from left to right from $1$ to $m$. We will denote a cell that is in the $i$-th row and in the $j$-th column as $(i, j)$. In the cell $(i, j)$ there is written a number $(i - 1) \cdot m + j$, that is $a_{ij} = (i - 1) \cdot m + j$.

翻译中…

A turtle initially stands in the cell $(1, 1)$ and it wants to come to the cell $(n, m)$. From the cell $(i, j)$ it can in one step go to one of the cells $(i + 1, j)$ or $(i, j + 1)$, if it exists. A path is a sequence of cells in which for every two adjacent in the sequence cells the following satisfies: the turtle can reach from the first cell to the second cell in one step. A cost of a path is the sum of numbers that are written in the cells of the path.

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image

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For example, with $n = 2$ and $m = 3$ the table will look as shown above. The turtle can take the following path: $(1, 1) \rightarrow (1, 2) \rightarrow (1, 3) \rightarrow (2, 3)$. The cost of such way is equal to $a_{11} + a_{12} + a_{13} + a_{23} = 12$. On the other hand, the paths $(1, 1) \rightarrow (1, 2) \rightarrow (2, 2) \rightarrow (2, 1)$ and $(1, 1) \rightarrow (1, 3)$ are incorrect, because in the first path the turtle can't make a step $(2, 2) \rightarrow (2, 1)$, and in the second path it can't make a step $(1, 1) \rightarrow (1, 3)$.

翻译中…

You are asked to tell the turtle a minimal possible cost of a path from the cell $(1, 1)$ to the cell $(n, m)$. Please note that the cells $(1, 1)$ and $(n, m)$ are a part of the way.

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Input

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The first line contains a single integer $t$ ($1 \leq t \leq 1000$) — the number of test cases. The description of test cases follows.

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A single line of each test case contains two integers $n$ and $m$ ($1 \leq n, m \leq 10^4$) — the number of rows and columns of the table $a$ respectively.

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Output

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For each test case output a single integer — a minimal possible cost of a path from the cell $(1, 1)$ to the cell $(n, m)$.

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Note

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In the first test case the only possible path consists of a single cell $(1, 1)$.

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The path with the minimal cost in the second test case is shown in the statement.

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In the fourth and the fifth test cases there is only one path from $(1, 1)$ to $(n, m)$. Both paths visit every cell in the table.

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样例

Input #1
7
1 1
2 3
3 2
7 1
1 10
5 5
10000 10000
Output #1
1
12
13
28
55
85
500099995000
InputCopy OutputCopy
题目信息
题号
1700A
时间限制
2 s
内存限制
256 MB
标签
构造
贪心
数学

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。