halshadshafds

arrays/src/arrays/Main.java

@@ -57,15 +57,13 @@ class Sudoku {
         for (int[] col : transposed)
             if (isRepetitive(col)) return false;
 
-        /*
+        // Check all 3x3 squares.
-       // Check there'ren't any repeats in a square.
+        for (int squareRow = 0; squareRow < 3; squareRow++) {
-   for (int i = 0; i < 9; i++) {
+            for (int squareCol = 0; squareCol < 3; squareCol++) {
-       int[] square = new int[3][3];
+                if (squareCheck(puz, squareRow * 3, squareCol * 3))
-       for (int j = i; j < i + 3; j++) {
+                    return false;
-           // for (int k = i; k < i + 3; k++) { square[i][k] }
             }
         }
-*/
 
         return true;
     }
@@ -91,6 +89,20 @@ class Sudoku {
 
         return transposed;
     }
+
+    // Check if a 3x3 square repeats values.
+    static boolean squareCheck(int[][] puz, int startRow, int startCol) {
+        HashMap<Integer, Boolean> seen = new HashMap<>();
+
+        for (int i = 0; i < 3; i++)
+            for (int j = 0; j < 3; j++) {
+                int val = puz[startRow + i][startCol + j];
+                if (seen.containsKey(val)) return true;
+                else seen.put(val, true);
+            }
+
+        return false;
+    }
 }
 
 class Examples {
@@ -166,6 +178,7 @@ class Examples {
         t.checkExpect(Sudoku.solved(testPuz6), false);
         t.checkExpect(Sudoku.solved(testPuz7), false);
     }
+
     void testSieve(Tester t) {
         Sieve sieve = new Sieve(29);
         t.checkExpect(sieve.hasNext(), true);

streams/src/streams/Main.java

@@ -2,7 +2,6 @@ package streams;
 
 import java.util.ArrayList;
 import java.util.Arrays;
-import java.util.Comparator;
 import java.util.List;
 import java.util.Map;
 import java.util.Optional;