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+--- Thread: (25) N-Queens (/thread-18092.html)
(25) N-Queens - Thomas Klemm - 03-02-2022 01:20 AM
References
The program is based on the flowcharts that are linked in Dave Britten's solution.
But I had to make some changes:
- the number format is \(0.a_1 a_2 \cdots a_8\)
- the indexes \(m_0\) and \(m_1\) are decremented so we can use comparison with \(0\)
- the number \(10\) is kept as a constant in register \(m_6\)
- storage arithmetic helped to save some steps
Registers
0: # of old queens
1: New queen
2: Old queens
3: Chopping block
4: i counter
5: n size of board
6: 10 as constant
Initialization and Run
CLEAR REG
FIX 8
8
STO 0
STO 5
10
STO 6
GTO 13
R/S
Solution
After about 40 minutes this result is shown:
0.57263148
This corresponds to the following setup:
5 7 2 6 3 1 4 8
8: | | | | | | | |#|
7: | |#| | | | | | |
6: | | | |#| | | | |
5: |#| | | | | | | |
4: | | | | | | |#| |
3: | | | | |#| | | |
2: | | |#| | | | | |
1: | | | | | |#| | |
The next solutions will be shown after starting the program again with R/S.
However for now it will not detect the end.
There simply was no memory left to do so.
Program
The program can be used in this HP-25C emulator.
Code:
01: 24 01 : RCL 1
02: 23 51 02 : STO + 2
03: 24 06 : RCL 6
04: 23 71 02 : STO / 2
05: 01 : 1
06: 23 41 00 : STO - 0
07: 24 00 : RCL 0
08: 15 61 : g x<>0
09: 13 13 : GTO 13
10: 24 02 : RCL 2
11: 74 : R/S
12: 13 36 : GTO 36
13: 24 05 : RCL 5
14: 23 01 : STO 1
15: 24 02 : RCL 2
16: 23 03 : STO 3
17: 34 : CLx
18: 23 04 : STO 4
19: 01 : 1
20: 23 51 04 : STO + 4
21: 24 06 : RCL 6
22: 23 61 03 : STO * 3
23: 24 03 : RCL 3
24: 15 71 : g x=0
25: 13 01 : GTO 01
26: 14 01 : f INT
27: 23 41 03 : STO - 3
28: 24 01 : RCL 1
29: 14 71 : f x=y
30: 13 36 : GTO 36
31: 41 : -
32: 15 03 : g ABS
33: 24 04 : RCL 4
34: 14 61 : f x<>y
35: 13 19 : GTO 19
36: 01 : 1
37: 23 41 01 : STO - 1
38: 24 01 : RCL 1
39: 15 61 : g x<>0
40: 13 15 : GTO 15
41: 01 : 1
42: 23 51 00 : STO + 0
43: 24 06 : RCL 6
44: 23 61 02 : STO * 2
45: 24 02 : RCL 2
46: 14 01 : f INT
47: 23 41 02 : STO - 2
48: 23 01 : STO 1
49: 13 36 : GTO 36RE: (25) N-Queens - Dave Britten - 03-02-2022 01:31 AM
Wow, impressive! I took a very brief stab at doing this, but I was about 20 steps over the limit, with no obvious way to trim any more fat.