diff --git a/src/sudoku.clj b/src/sudoku.clj
index 5254c46..8319635 100644
--- a/src/sudoku.clj
+++ b/src/sudoku.clj
@@ -3,56 +3,119 @@
 
 (def board identity)
 
+
+
+(def all-values #{1 2 3 4 5 6 7 8 9})
+
 (defn value-at [board coord]
-  nil)
+  (get-in board coord))
 
 (defn has-value? [board coord]
-  nil)
+  (if (== (value-at board coord) 0)
+    false
+    true))
 
 (defn row-values [board coord]
-  nil)
+  (let [[col _] coord]
+    (set (map (fn [row]
+                (get-in board [col row])) (range 9)))))
 
 (defn col-values [board coord]
-  nil)
+  (let [[_ row] coord]
+    (set (map (fn [col]
+           (get-in board [col row])) (range 9)))))
 
 (defn coord-pairs [coords]
-  nil)
+  (for [col coords
+        row coords]
+    [col row]))
 
 (defn block-values [board coord]
-  nil)
+  (let [upper-right (fn [[x y]]
+                      (cond
+                        (< x 3)
+                          (cond
+                            (< y 3)
+                              [0 0]
+                            (< y 6)
+                              [0 3]
+                            :else
+                              [0 6])
+                        (< x 6)
+                          (cond
+                            (< y 3)
+                              [3 0]
+                            (< y 6)
+                              [3 3]
+                            :else
+                              [3 6])
+                        :else
+                          (cond
+                            (< y 3)
+                              [6 0]
+                            (< y 6)
+                              [6 3]
+                            :else
+                              [6 6])))]
+    (let [rangex (map (fn [number] (+ number (first (upper-right coord)))) [0 1 2])
+          rangey (map (fn [number] (+ number (second (upper-right coord)))) [0 1 2])]
+      (set (for [x rangex
+            y rangey]
+        (value-at board [x y]))))))
 
 (defn valid-values-for [board coord]
-  nil)
+  (if (has-value? board coord)
+    #{}
+    (set/difference all-values (set/union (block-values board coord) (row-values board coord) (col-values board coord)))))
 
 (defn filled? [board]
-  nil)
+    (boolean (not (some true? (for [x (range 9)]
+      (contains? (row-values board [x 0]) 0))))))
 
 (defn rows [board]
-  nil)
+  (for [x (range 9)]
+    (row-values board [x 0])))
 
 (defn valid-rows? [board]
-  nil)
+  (every? true? (for [x (range 9)]
+    (and (not (contains? (row-values board [x 0]) 0)) (== 9 (count (row-values board [x 0])))))))
 
 (defn cols [board]
-  nil)
+  (for [x (range 9)]
+    (col-values board [0 x])))
 
 (defn valid-cols? [board]
-  nil)
+  (every? true? (for [x (range 9)]
+    (and (not (contains? (col-values board [0 x]) 0)) (== 9 (count (col-values board [0 x])))))))
 
 (defn blocks [board]
-  nil)
+  (for [x [0 3 6]
+        y [0 3 6]]
+    (block-values board [x y])))
 
 (defn valid-blocks? [board]
-  nil)
+  (every? true? (for [x [0 3 6]
+                      y [0 3 6]]
+    (and (not (contains? (block-values board [x y]) 0)) (== 9 (count (block-values board [x y])))))))
 
 (defn valid-solution? [board]
-  nil)
+  (and (valid-blocks? board) (valid-rows? board) (valid-cols? board)))
 
 (defn set-value-at [board coord new-value]
-  nil)
+  (assoc-in board coord new-value))
 
 (defn find-empty-point [board]
-  nil)
+  (first (remove nil? (set (for [x (range 9)
+        y (range 9)]
+    (if (has-value? board [x y])
+      nil
+      [x y]))))))
 
 (defn solve [board]
-  nil)
+    (if (valid-solution? board)
+      board
+      (let [empty-point (find-empty-point board)]
+        (for [value (valid-values-for board empty-point)
+          solved (solve (set-value-at board empty-point value))]
+          solved))))
+