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June 2018 Update

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Ingy döt Net 2018-06-22 20:57:24 +00:00
parent ba8067c3b7
commit 22f33d4004
5278 changed files with 84726 additions and 14379 deletions
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41
Task/N-queens-problem/Stata/n-queens-problem-3.stata
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@ -1,5 +1,5 @@
mata
real matrix queens(real scalar n) {
real matrix queens_rec(real scalar n) {
real rowvector a, u, v
real matrix m
@ -13,46 +13,25 @@ real matrix queens(real scalar n) {
void queens_aux(real scalar n, real scalar i, real rowvector a,
real rowvector u, real rowvector v, real matrix m) {
real scalar j, k, s
real scalar j, k
if (i > n) {
m = m\a
} else {
for (k = i; k <= n; k++) {
j = a[k]
p = i+j-1
q = i-j+n
for (j = i; j <= n; j++) {
k = a[j]
p = i-k+n
q = i+k-1
if (u[p] & v[q]) {
u[p] = v[q] = 0
s = a[i]
a[i] = a[k]
a[k] = s
a[j] = a[i]
a[i] = k
queens_aux(n, i+1, a, u, v, m)
u[p] = v[q] = 1
s = a[i]
a[i] = a[k]
a[k] = s
a[i] = a[j]
a[j] = k
}
}
}
}
a = queens(8)
e = I(8)
1:/e[a[1,.],.]
1 2 3 4 5 6 7 8
+---------------------------------+
1 | 1 . . . . . . . |
2 | . . . . 1 . . . |
3 | . . . . . . . 1 |
4 | . . . . . 1 . . |
5 | . . 1 . . . . . |
6 | . . . . . . 1 . |
7 | . 1 . . . . . . |
8 | . . . 1 . . . . |
+---------------------------------+
rows(a)
92
end