Codeforces Round 801 (Div. 2) and EPIC Institute of Technology Round
C
Zero Path
Codeforces
1700
原题
← BD1 →
翻译中…

You are given a grid with $n$ rows and $m$ columns. We denote the square on the $i$-th ($1\le i\le n$) row and $j$-th ($1\le j\le m$) column by $(i, j)$ and the number there by $a_{ij}$. All numbers are equal to $1$ or to $-1$.

翻译中…

You start from the square $(1, 1)$ and can move one square down or one square to the right at a time. In the end, you want to end up at the square $(n, m)$.

翻译中…

Is it possible to move in such a way so that the sum of the values written in all the visited cells (including $a_{11}$ and $a_{nm}$) is $0$?

翻译中…

image

翻译中…

Input

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Each test contains multiple test cases. The first line contains the number of test cases $t$ ($1 \leq t \leq 10^4$). Description of the test cases follows.

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The first line of each test case contains two integers $n$ and $m$ ($1 \le n, m \le 1000$)  — the size of the grid.

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Each of the following $n$ lines contains $m$ integers. The $j$-th integer on the $i$-th line is $a_{ij}$ ($a_{ij} = 1$ or $-1$)  — the element in the cell $(i, j)$.

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It is guaranteed that the sum of $n\cdot m$ over all test cases does not exceed $10^6$.

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Output

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For each test case, print "YES" if there exists a path from the top left to the bottom right that adds up to $0$, and "NO" otherwise. You can output each letter in any case.

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Note

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One possible path for the fourth test case is given in the picture in the statement.

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样例

Input #1
5
1 1
1
1 2
1 -1
1 4
1 -1 1 -1
3 4
1 -1 -1 -1
-1 1 1 -1
1 1 1 -1
3 4
1 -1 1 1
-1 1 -1 1
1 -1 1 1
Output #1
NO
YES
YES
YES
NO
InputCopy OutputCopy
题目信息
题号
1695C
时间限制
2 s
内存限制
256 MB
标签
暴力
数据结构
动态规划
图论
贪心
最短路

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