Can anyone explain me test #1;
London keeps 1st from day 12 to 21 (10 days) and 23 to 25 (3 days). Day 22th London = StPetersburg (=15b). Why output is London 14?

The leaders are:
 1- 1 London
 2- 5 [tie]
 6-10 Anadyr
11-11 Moscow
12-15 London
16-20 London
21-21 London
22-22 [tie]
23-25 London

It seems you missed day 1.