词搜索算法的MATLAB [英] word search algorithm matlab

问题描述

我在寻找一个有效的字搜索算法。如果你能帮助我想出它的话会更好。

I am looking for an efficient word search algorithm. If you can help me come up with it it would be even better

a h c k 
x r j i
b v t l
c y q s

和我想找到'艺术'。如果斯特拉也是一个有效的话，我希望这样的发现为好。 （垂直，水平，对角线和反向）。我想出了一些算法，但你似乎并不有效，长期食用编码。使用find（）来获得的第一个字母，并期待在该列或行的第一个包括在内。

and I want to find 'arts' . If 'stra' was also a valid word I want that to be found as well. (vertical, horizontal, diagonal and reverse). I came up with a few algorithms but thy don't seem efficient and consume long coding. First one included using find() to get the first letter and look at that column or rows.

推荐答案

这里有一种方法：

%// Example word grid
C = [
    'a' 'h' 'c' 'k' 'r'
    'x' 'r' 'j' 'i' 'p'
    'b' 'v' 't' 'l' 'q'
    'a' 'y' 'q' 's' 'o'];

%// Your search term
target = 'arts';

%// Optionally, do some obvious checks here. 
%//  - length of the search string may exceeds the grid's dimensions
%//  - there are no matches for the first letter
%//  - and similar

%// Form single cellstring containing all search directions
allDirections = [
    %{
    // horizontal, horizontal-reversed
    %}
    cellstr([C ; C(:,end:-1:1)])
    %{
    // vertical, vertical-reversed
    %}
    cellstr([C'; C(:,end:-1:1)']) 
    %{
    // Diagonal, top-left to bottom-right, and reversed
    %}
    arrayfun(@(ii){diag(C,ii)'}, -size(C,1)+2:size(C,2)-2)';
    arrayfun(@(ii){diag(C(end:-1:1,end:-1:1),ii)'}, -size(C,1)+2:size(C,2)-2)';
    %{
    // Diagonal, top-right to bottom-left, and reversed
    %}
    arrayfun(@(ii){diag(C(:,end:-1:1),ii)'}, -size(C,1)+2:size(C,2)-2)';
    arrayfun(@(ii){diag(C(end:-1:1,:),ii)'}, -size(C,1)+2:size(C,2)-2)';
];

%// And now just find the string
strfind(allDirections , target)

通过

当然，你可以改善（内存）的效率

• 执行 strfind 上的所有单独路线
• 在做2× strfind 在同一个方向，但与目标倒
• 等。
• doing the strfind on all the directions separately
• doing 2 × strfind on the same direction, but with the target inverted
• etc.

但是，除了这些相对次要的优化，我不认为你可以在实践中做到MATLAB中的更好的。

But aside from these relatively minor optimizations, I don't think you can do much better in MATLAB in practice.

一个理论上更高效的递归，分支和绑定类型的搜索大致是这样的：

A theoretically more efficient recursive, branch-and-bound type search roughly goes like this:

• 找到的第一个字母出现的所有
• 在消除所有不能满足目标的长度那些出现的基于网格的尺寸
• 搜索全部命中的社区是否出现的第二个字母
• 在消除基于长事件，等等。
• find all occurrences of the first letter
• eliminate all of those occurrences that cannot satisfy the length of the target based on the dimensions of the grid
• Search the neighborhoods of all hits for occurrences of the second letter
• Eliminate occurrences based on length, etc.

（不要忘了在过滤的方向的第二个字母后，作为命中的第二个字母修复搜索方向）

(Don't forget to filter on direction after the second letter, as the hits for the second letter fixes the search directions)

据我所看到的，这将需要大量的少读和比较，比我的版本。但是，我的猜测是，使用固定程序（像我一样）将是更快和更复杂的比使用（嵌套）循环。但我可能是错的。

As far as I can see, this would need a lot less reads and comparisons than my version. However, my guess would be that using canned routines (as I did) is going to be faster and less complicated than using (nested) loops. But I could be wrong.

尝试。个人资料。学习。微笑。指正:)

Try. Profile. Learn. Smile. Correct me :)

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