refactor group representation

tests.py

@@ -0,0 +1,16 @@
+import time
+
+import groups
+
+if __name__ == '__main__':
+    g = groups.T(100)
+
+    s = time.time()
+    table = g.solve()
+    e = time.time()
+
+    print(f'elapsed = {e - s:.3g}s')
+
+    print(len(table))
+    if len(table) < 20:
+        print(table)