Data commit

Task/N-queens-problem/Zig/n-queens-problem.zig

@@ -0,0 +1,40 @@
+const std = @import("std");
+const stdout = std.io.getStdOut().outStream();
+
+var board = [_]i8{-1} ** 8;
+
+inline fn abs(x: var) @TypeOf(x) {
+    return if (x < 0) -x else x;
+}
+
+fn safe(c: i32, r: i32) bool {
+    var i: i32 = 0;
+    return while (i < c) : (i += 1) {
+        const q = board[@intCast(u3, i)];
+        if (r == q or c == i + abs(q - r))
+            break false;
+    } else true;
+}
+
+pub fn main() !void {
+    var i: i32 = 0;
+    while (i >= 0) {
+        var j = board[@intCast(u3, i)] + 1;
+        while (j < 8) : (j += 1) {
+            if (safe(i, j)) {
+                board[@intCast(u3, i)] = j;
+                i += 1;
+                break;
+            }
+        } else {
+            board[@intCast(u3, i)] = -1;
+            i -= 1;
+        }
+        if (i == 8) { // found a solution
+            for (board) |q|
+                try stdout.print("{} ", .{q + 1});
+            try stdout.print("\n", .{});
+            i -= 1; // create a failure to try new solutions.
+        }
+    }
+}