Max/Min values in an associative array

[TJB via Digitalmars-d-learn]

I am trying to find the max and min values in an associative 
array. Say I have:

double[char] bids;
bid['A'] = 37.50;
bid['B'] = 38.11;
bid['C'] = 36.12;

How can I find the max and min values. I am thinking that I need 
to use max and min functions from std.algorithm, but not sure how 
to.

Thanks!
TJB