43.3.2

43/43.3.1.scm

@@ -1,5 +1,9 @@
 #lang racket
 
+(provide
+  board-for-all
+  place-queen)
+
 (define (board-for-all f board)
   (local ((define N (vector-length board)))
     (for-each (lambda (i)
@@ -45,4 +49,4 @@
     )
    ))
 
-(exit (run-tests place-queen-tests))
+(run-tests place-queen-tests)

43/43.3.2.scm

@@ -0,0 +1,40 @@
+#lang racket
+
+(require "43.3.1.scm")
+
+(define (unplace-queen board i j)
+  (board-for-all
+    (lambda (I J x)
+      (cond [(or (= i I)
+                 (= j J)
+                 (= (+ i j) (+ I J))
+                 (= (- i j) (- I J))) true]
+            [else x]))
+    board))
+
+(require rackunit)
+(require rackunit/text-ui)
+
+(define unplace-queen-tests
+  (test-suite
+   "Test for unplace-queen"
+
+   (test-case
+    ""
+    (define board
+      (build-vector
+        3
+        (lambda (i)
+          (build-vector
+            3
+            (lambda (j) false)))))
+    (unplace-queen board 0 0)
+    (check-equal?
+      board
+      '#(#(#t #t #t)
+         #(#t #t #f)
+         #(#t #f #t)))
+    )
+   ))
+
+(exit (run-tests unplace-queen-tests))