为O（n ^ 2），如果我没有看错！

为什么你需要两个内环是超越我。为什么不总结B和C在同一个循环？

procedure matrixvector(n:integer);
var i,j:integer;
begin
  for i<-1 to n do begin
    B[i] = 0;
    C[i] = 0;
    for j<-1 to i do 
      B[i]<- B[i]+ A[i,j];
    for j<-n down to i+1 do
      C[i]<-C[i] + A[i,j]
  end
end;

O(n^2), if I read it right.

Why you need two inner loops is beyond me. Why not sum B and C in the same loop?