Wei-Hwa's Solitaire Battleships Times, and some Battleships Strategies

Introduction

As a member of the US World Puzzle Team, I thought I could use more practice on Battleships puzzles, seeing as how I thought there was room for improvement.

One way was that I bought the book Solitaire Battleships, with a whopping 108 puzzles, ordered by category. I grabbed a pen and started doing these puzzles and timing myself during my daily commutes. After about a week, I had finished all puzzles (I commute about 2 hours every day). The total time spent was about eight hours, so I estimate two hours were spend in between puzzles while writing my times down. That sounds about right -- and that's an average of four and a half-minutes per puzzle! Not bad, considering I spent more than half an hour on one puzzle alone.

A few notes on how I solved them

Since this was practice for a timed situation, I used every trick I knew. If I got a solution, I didn't bother checking if it was unique. I (ab)used the uniqueness assumption many times.

If you're just starting with Battleships problems, I suggest reading the very good introduction in the book Solitaire Battleships. It tells you about all logical techniques (that I know of) that can help you solve Battleships problems, with the dubious exception of the uniqueness assumption (it mentions it in passing, but doesn't delve into the intricacies of it and you could easily miss the mention).

Even with the uniqueness assumption (which doesn't come in use that often), I believe that there is no fast way to solve certain Battleships problems with only logical techniques. At least, not if you want to solve the tough problems in less than five minutes. So what techniques did I use? I can think of a few which I'll describe below.

The first is to get an instinctual feel for when you've reached a dead end. This just requires a lot of practice to build up your intuition. While solving, I often guessed a location for a ship and quickly felt "Hmm, I think I'll get stuck if I keep on going." I would then whip out the eraser and try another location. Occasionally my instincts were wrong and I ended up eliminating the correct answer, which explains some of the horrible times on some of these problems!

This means that to do well, you must also learn to distinguish between dead-ends that you're confident on and ones that you're not, so you know which path to go down if you get stuck having eliminated all possible paths. If you're confident that such-and-such a guess was wrong, don't revisit it; but if you're not so confident, by all means revisit it when you've exhausted all other options!

The second technique is to learn about "piece swapping." I'll write a whole new page about it, since this is pretty useful but will need some graphics. It's worth mentioning that it doesn't work very well with the awesome Battleships software Fathom It! though.

The data

To share, I've placed my data below. Feel free to compare your times against mine.

A few things are worth mentioning:

Overall Statistics:
Difficulty Mean Sdev Median Min Max Midrange
Seaman 01:16 00:31 01:06 00:40 02:31 01:35
Petty Officer 01:53 00:42 01:42 01:12 03:40 02:26
Ensign 02:32 01:13 02:15 01:02 06:02 03:32
Captain 04:32 06:38 02:01 01:15 28:55 15:05
Captain/no 62 03:15 03:25 02:01 01:15 16:01 08:38
Commodore 04:01 02:14 03:14 01:10 09:24 05:17
Admiral 12:31 12:09 06:46 02:14 36:41 19:27
All 04:24 06:32 02:16 00:40 36:41 18:41

Raw Data:
Num Difficulty Time
1 Seaman 00:48
2 Seaman 01:07
3 Seaman 02:31
4 Seaman 00:45
5 Seaman 01:03
6 Seaman 00:40
7 Seaman 01:44
8 Seaman 01:04
9 Seaman 01:39
10 Seaman 01:19
11 Seaman 01:06
12 Seaman 01:22
13 Petty Officer 01:30
14 Petty Officer 03:40
15 Petty Officer 01:12
16 Petty Officer 01:15
17 Petty Officer 02:06
18 Petty Officer 02:00
19 Petty Officer 01:40
20 Petty Officer 01:32
21 Petty Officer 01:13
22 Petty Officer 01:13
23 Petty Officer 01:25
24 Petty Officer 02:02
25 Petty Officer 02:56
26 Petty Officer 01:40
27 Petty Officer 01:46
28 Petty Officer 02:58
29 Petty Officer 01:45
30 Petty Officer 02:44
31 Petty Officer 01:12
32 Petty Officer 02:01
33 Ensign 02:05
34 Ensign 05:15
35 Ensign 02:32
36 Ensign 01:20
37 Ensign 02:19
38 Ensign 02:06
39 Ensign 06:02
40 Ensign 02:38
41 Ensign 01:56
42 Ensign 02:36
43 Ensign 02:43
44 Ensign 02:12
45 Ensign 02:24
46 Ensign 01:02
47 Ensign 02:12
48 Ensign 02:35
49 Ensign 02:06
50 Ensign 01:32
51 Ensign 01:19
52 Ensign 03:43
53 Captain 01:48
54 Captain 06:26
55 Captain 01:27
56 Captain 05:22
57 Captain 01:39
58 Captain 01:15
59 Captain 03:12
60 Captain 01:48
61 Captain 01:39
62 Captain 28:55
63 Captain 01:45
64 Captain 03:01
65 Captain 02:01
66 Captain 02:31
67 Captain 04:43
68 Captain 01:25
69 Captain 02:03
70 Captain 01:45
71 Captain 02:02
72 Captain 16:01
73 Commodore 02:32
74 Commodore 01:10
75 Commodore 04:36
76 Commodore 06:06
77 Commodore 06:10
78 Commodore 06:17
79 Commodore 09:24
80 Commodore 01:44
81 Commodore 02:42
82 Commodore 03:06
83 Commodore 01:40
84 Commodore 07:41
85 Commodore 05:35
86 Commodore 04:13
87 Commodore 02:42
88 Commodore 03:13
89 Commodore 02:33
90 Commodore 01:27
91 Commodore 04:07
92 Commodore 03:15
93 Admiral 05:26
94 Admiral 02:14
95 Admiral 09:26
96 Admiral 04:24
97 Admiral 09:26
98 Admiral 02:31
99 Admiral 30:30
100 Admiral 03:10
101 Admiral 02:42
102 Admiral 06:03
103 Admiral 32:05
104 Admiral 07:29
105 Admiral 02:31
106 Admiral 36:41
107 Admiral 19:39
108 Admiral 26:00

By Wei-Hwa Huang
Last Modified on July 2, 1999