Add: julia-0.6.2

Former-commit-id: ccc667cf67d569f3fb3df39aa57c2134755a7551

julia-0.6.2/share/doc/julia/examples/queens.jl

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+# This file is a part of Julia. License is MIT: https://julialang.org/license
+
+# n-queens (nqueens) solver, for nsquaresx-by-nsquaresy board
+
+struct Queen
+    x::Int
+    y::Int
+end
+hitshorz(queena, queenb) = queena.x == queenb.x
+hitsvert(queena, queenb) = queena.y == queenb.y
+hitsdiag(queena, queenb) = abs(queena.x - queenb.x) == abs(queena.y - queenb.y)
+hitshvd(qa, qb) = hitshorz(qa, qb) || hitsvert(qa, qb) || hitsdiag(qa, qb)
+hitsany(testqueen, queens) = any(q -> hitshvd(testqueen, q), queens)
+
+function trysolve(nsquaresx, nsquaresy, nqueens, presqueens = ())
+    nqueens == 0 && return presqueens
+    for xsquare in 1:nsquaresx
+        for ysquare in 1:nsquaresy
+            testqueen = Queen(xsquare, ysquare)
+            if !hitsany(testqueen, presqueens)
+                tryqueens = (presqueens..., testqueen)
+                maybesol = trysolve(nsquaresx, nsquaresy, nqueens - 1, tryqueens)
+                maybesol !== nothing && return maybesol
+            end
+        end
+    end
+    return nothing
+end