How do i this in an efficient way?

I want get C

A=[13.89 32.56  23.09  22.02  32.06  20.81  
   28.16 29.97  29.12  29.83   9.21  24.21  
   18.60 26.93  7.07  18.87  16.16  21.38  
   17.00 31.00  23.00  24.17  12.21  25.32  
   9.49   17.09  15.81   8.00  13.45  26.00  
   43.0  35.17  16.16  39.00   10.05  18.87];

B=[2 5 6 1 5 3];

C=A(B(1),B(2))+A(B(2),B(3))+A(B(3),B(4))+A(B(4),B(5))+A(B(5),B(6))

Answer 1

[James Tursa]

C = sum(A(sub2ind(size(A),B(1:end-1),B(2:end))));