% A=randperm(20,5);
A=[20,13,7,4,6];
%%%升序排列
for m=2:length(A)
    key=A(m);
    n=m-1;
    while n>0&&A(n)>key
        A(n+1)=A(n);
        n=n-1;
    end
    A(n+1)=key;
end
%%%降序排列
%%
A=[20,13,7,4,6];
for m=2:length(A)
    key=A(m);
    n=m-1;
    while n>0&&A(n)<key
        A(n+1)=A(n);
        n=n-1;
    end
    A(n+1)=key;