Data commit

Task/N-queens-problem/Wren/n-queens-problem.wren

@@ -0,0 +1,38 @@
+var count = 0
+var c = []
+var f = []
+
+var nQueens // recursive
+nQueens = Fn.new { |row, n|
+    for (x in 1..n) {
+        var outer = false
+        var y = 1
+        while (y < row) {
+            if ((c[y] == x) || (row - y == (x -c[y]).abs)) {
+                outer = true
+                break
+            }
+            y = y + 1
+        }
+        if (!outer) {
+            c[row] = x
+            if (row < n) {
+                nQueens.call(row + 1, n)
+            } else {
+                count = count + 1
+                if (count == 1) f = c.skip(1).map { |i| i - 1 }.toList
+            }
+        }
+    }
+}
+
+for (n in 1..14) {
+    count = 0
+    c = List.filled(n+1, 0)
+    f = []
+    nQueens.call(1, n)
+    System.print("For a %(n) x %(n) board:")
+    System.print("  Solutions = %(count)")
+    if (count > 0) System.print("  First is %(f)")
+    System.print()
+}