What is wrong with my code? Cycle while help

Given a matrix called 'Heights' we should answer with a matrix called 'Path' that goes from space Heights(1,1) to space Height(m,n).

Matrix 'Heights'
   10 | 12 | 15 
  ---------------
   11 | 11 | 12
  ---------------
   13 | 14 | 15

So we are in Heights(1,1) and we can only move only - East - Southeast - South - (if the spaces have the same values we preferred first Southeast then East then South)

Matrix 'Path'
      1  1  10
      2  2  11
      2  3  12
      3  3  15

The code:

function Path = get_path(Heights)
        m = 1;
        n = 1;
        M = [1,1,Heights(1,1)];

          % Southwest = Heights(m+1,n+1)
          %      East = Heights(m,n+1)
          %     South = Heights(m+1,n)

          while m <= size(Heights,1) && n <= size(Heights,2)

              if m < size(Heights,1) && n < size(Heights,2)
                  if Heights(m+1,n+1) <= Heights(m,n+1) && Heights(m+1,n+1) <= Heights(m+1,n)
                      M = [M; m+1,n+1,Heights(m+1,n+1)];
                  elseif Heights(m+1,n+1) <= Heights(m,n+1) && Heights(m+1,n+1) > Heights(m+1,n)
                      M = [M; m+1,n,Heights(m+1,n)];
                  elseif Heights(m+1,n+1) > Heights(m,n+1) && Heights(m,n+1) <= Heights(m+1,n)
                      M = [M; m,n+1,Heights(m,n+1)];
                  elseif Heights(m+1,n+1) > Heights(m,n+1) && Heights(m,n+1) > Heights(m+1,n)
                      M = [M; m+1,n,Heights(m+1,n)];
                  end

              elseif m == size(Heights,1) && n < size(Heights,2)
                  M = [M; m,n+1,Altitudes(m,n+1)];

              elseif m < size(Heights,1) && n == size(Heights,2)
                  M = [M; m+1,n,Heights(m+1,n)];

              elseif m == size(Heights,1) && n == size(Heights,2)
                  M = [M; m,n,Heights(m,n)];

              end
          end

          Caminho = M

end

The problem is when I go to the command line and call the function is just stays blank...

Answer 1

[James Tursa]

You need to break out of the loop when you hit the bottom corner. Also, you need to add in code that updates m and/or n as you build the path. E.g.,

              elseif m < size(Heights,1) && n == size(Heights,2)
                  M = [M; m+1,n,Heights(m+1,n)];
                  m = m + 1;  % <-- add code like this to other branches also

 %              elseif m == size(Heights,1) && n == size(Heights,2)  <-- don't need this
 %                  M = [M; m,n,Heights(m,n)];

              end

              if m == size(Heights,1) && n == size(Heights,2)
                  break;
              end

Your current code is an infinite loop. Stepping through the code with the debugger and examining m, n, and M as you go would have shown you this.

What is "Altitudes"? Is that a typo?

[Jaquim Cigano]

Thank you so much! I was trying to solve this since yesterday!