June 2018 Update

Task/N-queens-problem/Sidef/n-queens-problem.sidef

@@ -0,0 +1,31 @@
+func N_queens_solution(N = 8) {
+
+    func collision(field, row) {
+        for i in (^row) {
+            var distance = (field[i] - field[row])
+            distance ~~ [0, row-i, i-row] && return true
+        }
+        return false
+    }
+
+    func search(field, row) {
+        row == N && return field
+        for i in (^N) {
+            field[row] = i
+            if (!collision(field, row)) {
+                return (__FUNC__(field, row+1) || next)
+            }
+        }
+        return []
+    }
+
+    for i in (0 .. N>>1) {
+        if (var r = search([i], 1)) {
+            return r
+        }
+    }
+}
+
+for n in (1..15) {
+    say "#{'%2d' % n}: #{N_queens_solution(n) || 'No solution'}"
+}