N-queens problem: Difference between revisions
m
→Python: Backtracking on permutations: Minor editing
m (→Python: backtracking on permutations: Adjusted a few final details) |
m (→Python: Backtracking on permutations: Minor editing) |
||
Line 12,887:
92</syntaxhighlight>
The preceding function does not enumerate solutions in lexicographic order, see [[Permutations#Recursive implementation]] for an explanation. The following does, but is almost 50% slower, because the exchange is always made (otherwise,
However, it may be interesting to look at the first solution in lexicographic order: for growing n, and apart from a +1 offset, it gets closer and closer to the sequence [http://oeis.org/A065188 A065188] at OEIS. The first n for which the first solutions differ is n=26.
Line 12,902:
yield from queen(i + 1)
b[i + j] = c[i - j] = True
a[i:(n - 1)], a[n - 1] = a[(i + 1):n], a[i]
else:
yield a
| |||