Special agent Alex and deputy director Bob are traveling on the Trans-Siberian Railway. They need to set up a secret meeting in Vladivostok at the usual time, 18:30. The only thing to decide is the day of the week. To this end, and to annoy Alex, Bob insists on playing a Battleships guessing game on a 20x20 grid. The rows are indexed 1-20, and the columns are indexed A-T. In this game one should correctly guess the location of 4 row boats of size 1x1 and 4 destroyers of size 1x4.
Alex, while not really fond of this idea, agrees. The game starts at 14:06 in the afternoon, by Bob firing at H20, which is a miss. The game goes on for several hours. Alex eats a sandwich after move 107; Bob falls asleep after move 109 but a cigar he enjoys after move 111 puts him back on track. After a couple of additional moves he suddenly stands up and announces that he will get off of the train at the next stop in Krasnoyarsk. After saying goodbye, Bob, as a word of advice, suggests Alex to check his phone. Alex does so: the phone shows 18:03.
Which day of the week will the two meet again (for a possible rematch)?
Here are the guesses of Bob in the format XYZ where X and Y are obvious coordinates and m, h, and s are responses from Alex indicating miss, hit, or sink:
H20m, L9m, B9m, O16m, I16m, K9m, D9m, L3m, Q18m, J8m, K10m, J18m, T15m, H17m, J12m, N18m, L16m, Q19s, O11m, K7m, P8m, P20m, C8m, I8h, I9h, I10h, I11s, C9m, P11m, D10m, T10m, I3m, H6m, K13m, K14m, I19m, P16m, H13m, H8m, J20m, O18m, I17m, J15m, C11m, M8m, I2m, Q15m, E11m, K8m, J6m, S15m, A12m, L5m, S12m, Q12m, K5m, M20m, F12m, L6m, A10m, O15m, E10m, H4m, I20m, F10m, O14m, Q8m, B11m, B12m, H11m, P17m, M19m, T11m, S14m, H10m, F8m, K11m, H2m, J5m, R18h, R17h, R16h, R15s, L14m, K17m, M9m, H18m, L12m, N17m, T12m, A8m, N16m, N13m, E9m, P15m, D11m, L8m, M16m, T16m, S10m, L18m, S17m, Q13m, L7m, I5m, N9m, N11m, K1m, I14m, K4m, S13m, K2m, H19m, R8m, S20m, B8m, T8m, H3m, J17m, I12m, J13m, T9m, O12m, Q10m, J1m.
And here are the guesses of Alex:
P1m, J20m, C12m, M9m, K19m, M18m, B4s, E5m, N8m, T1m, M6m, T5m,G13m, L5m, J18m, G17m, S8s, G7m, A18m, G18m, K4m, D2m, A16m, M5m,T3m, I9m, O10m, J5m, M7m, B8m, I14m, L12m, A5m, G5m, N5m, P15m, D4m, N18m, D12m, T2m, K15m, T10m, F4m, E3m, I11m, E15m, P10m, E16m, T6m, G2m, S6m, G6m, M1m, S9m, Q2m, P3m, Q4m, L15m, B17m, I20m, K12m, F7m, R14m, B6m, H12m, R18m, J6m, N20m, L18m, D3m, C19m, G9m, J1m, R8m, E11m, N13m, H3m, B7m, Q3m, I4m, A10m, Q13m, J14m, E13m, L1m, C20m, O12m, R13m, A7m, T15m, C3m, L20m, R15m, C5m, P11m, B12m, H5m, O4m, C16m, O1m, F12m, G3m, N6m, E14m, F8m, M19m, M17s, N11m, L16m, R20m, T13m, R2m, M2m, D16m, L9m, C14m, T17m, Q7m, H6m, O8m, P20m, P18m, D7m, B11m.
