how to test We are given a two$-$dimensional board of size N$$M $($ N rows and M columns$).$ Each field of the board can be empty $((.)),$ may contain an obstacle $(\text{'}$X$\text{'})$ or may have a character in it$.$ The character might be either an assassin $(\text{'}$A$\text{'})$ or a guard. Each guard stands still and looks straight ahead, in the direction they are facing. Every guard looks in one of four directions $($up$,$ down, left or right on the board$)$ and is represented by one of four symbols. A guard denoted by $\text{'}$e$\text{'}$ is looking to the left; by $\text{'}>\text{'},$ to the right; $\text{'}\text{'}$c$\text{'},$ up; or $\text{'}$ v $\text{'},$ down. The guards can see everything in a straight line in the direction in which they are facing, as far as the first obstacle $(\text{'}$X$\text{'}$ or any other guard$)$ or the edge of the board. The assassin can move from the current field to any other empty field with a shared edge. The assassin cannot move onto fields containing obstacles or enemies. Write a function: class Solution $\backslash \{$ public boolean solution$($String$[]$ B$)$; $\backslash \}$ that, given an array B consisting of N strings denoting rows of the array, returns true if is it possible for the assassin to sneak from their current location to the bottom$-$right cell of the board undetected, and false otherwise. Examples: $1.$ Given B$=[\text{'}$X$.....>,",.$v$...$X$.",".>...$X$..","$A$......"],$ your function should return false. All available paths lead through a field observed by a guard. $2.$ Given B$=[...$Xv$,"$AX$..$ A$",".$ XX$.."],$ your function should return true. The guard in the second row is blocking the other one from watching the bottom$-$right square. $3.$ Given B$=[,...,">,$A$],$ your function should return false, as the assassin gets spotted right at the start. $4.$ Given B $=[\text{'}$A$.$v$",..."],$ your function should return false. It's not possible for the assassin to enter the bottom$-$right cell undetected, as the cell is observed. Write an efficient algorithm for the following assumptions: $-$ N is an integer within the range $[1.\mathrm{.}500]$; $-$ all strings in B are of the same length M from range $[1.\mathrm{.}500]$; $-$ there is exactly one assassin on the board; $-$ there is no guard or wall on B$[$N$1][$M$1]$; $-$ every string in B consists only of the following characters $\text{'}..,\text{'}$X$\text{'},\text{'}<\text{'},\text{'}>\text{'},\text{'}$v$\text{'},\text{'}\text{'}$n$\text{'}$ and$/$or $\text{'}$A$\text{'}.$

Guards can appear the following way in the matrix: $\text{'}<\text{'}$ represents a guard that is looking to the left, $\text{'}>\text{'}$ represents a guard that is looking to the right, $\text{'}^\text{'}$ looks up$,$ and $\text{'}$v$\text{'}$ is looking down. Their line of sight extends as long as there is an obstacle, edge of the matrix or another guard.

Write a function that calculates whether the assassin can reach the bottom$-$right corner of the matrix. The assassin can not step in the line of sight of any guard.