no-cache.py

# global cache removed

import time
start_time = time.time()
#
def get_eq_map(vals):
    # Given a list of floating point values, returns a map from result values
    # to an equation string returning that result.
    if len(vals) == 1:
        return {vals[0]: str(vals[0])}
    else:
        eq_map = {}
        for i in range(1, len(vals)):
            head_eq_map = get_eq_map(vals[:i])
            tail_eq_map = get_eq_map(vals[i:])
            for h,heq in head_eq_map.iteritems():
                heq2 = "(" + heq
                for t,teq in tail_eq_map.iteritems():
                    teq2 = teq + ")"
                    eq_map[h + t] = heq2 + "+" + teq2
                    eq_map[h - t] = heq2 + "-" + teq2
                    eq_map[h * t] = heq2 + "*" + teq2
                    if t != 0:
                        eq_map[h / t] = heq2 + "/" + teq2
        return eq_map
#
all_vals = get_eq_map([float(x) for x in range(1, 10)])
print 'Time:', time.time() - start_time
print 'Total number of values', len(all_vals)
for i in (float(x) for x in range(1900, 2101)):
    if i in all_vals:
        print i, all_vals[i]
    else:
        print i, 'None'