Codeforces Round 355 (Div. 2)
E
Vanya and Balloons
Codeforces
2300
原题
← D→
翻译中…

Vanya plays a game of balloons on the field of size $*n* × *n*$, where each cell contains a balloon with one of the values $0$, $1$, $2$ or $3$. The goal is to destroy a cross, such that the product of all values of balloons in the cross is maximum possible. There are two types of crosses: normal and rotated. For example:

翻译中…

**o**
**o**
ooooo
**o**
**o**

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or

翻译中…

o***o
*o*o*
**o**
*o*o*
o***o

翻译中…

Formally, the cross is given by three integers $*r*$, $*c*$ and $*d*$, such that $*d* ≤ *r*, *c* ≤ *n* - *d* + 1$. The normal cross consists of balloons located in cells $(*x*, *y*)$ (where $*x*$ stay for the number of the row and $*y*$ for the number of the column), such that $|*x* - *r*|·|*y* - *c*| = 0$ and $|*x* - *r*| + |*y* - *c*| < *d*$. Rotated cross consists of balloons located in cells $(*x*, *y*)$, such that $|*x* - *r*| = |*y* - *c*|$ and $|*x* - *r*| < *d*$.

翻译中…

Vanya wants to know the maximum possible product of the values of balls forming one cross. As this value can be large, output it modulo $10^{9} + 7$.

翻译中…

Input

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The first line of the input contains a single integer $*n*$ ($1 ≤ *n* ≤ 1000$) — the number of rows and columns in the table with balloons.

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The each of the following $*n*$ lines contains $*n*$ characters '0', '1', '2' or '3' — the description of the values in balloons.

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Output

翻译中…

Print the maximum possible product modulo $10^{9} + 7$. Note, that you are not asked to maximize the remainder modulo $10^{9} + 7$, but to find the maximum value and print it this modulo.

翻译中…

Note

翻译中…

In the first sample, the maximum product is achieved for a rotated cross with a center in the cell $(3, 3)$ and radius $1$: $2·2·3·3·3 = 108$.

翻译中…

样例

Input #1
4
1233
0213
2020
0303
Output #1
108
InputCopy OutputCopy
Input #2
5
00300
00300
33333
00300
00300
Output #2
19683
InputCopy OutputCopy
Input #3
5
00003
02030
00300
03020
30000
Output #3
108
InputCopy OutputCopy
Input #4
5
21312
10003
10002
10003
23231
Output #4
3
InputCopy OutputCopy
Input #5
5
12131
12111
12112
21311
21212
Output #5
24
InputCopy OutputCopy
题目信息
题号
677E
时间限制
3 s
内存限制
512 MB
标签
二分
暴力
动态规划
模拟

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。