Allow moves violating superko to be played; only enforce basic ko rule.

featurecat · Oct 27, 2018 · 10ada67 · 10ada67
1 parent 322cf17
commit 10ada67
Show file tree

Hide file tree

Showing 2 changed files with 7 additions and 1 deletion.
diff --git a/src/main/java/featurecat/lizzie/rules/Board.java b/src/main/java/featurecat/lizzie/rules/Board.java
@@ -399,7 +399,7 @@ public void place(int x, int y, Stone color, boolean newBranch) {
               0);
 
       // don't make this coordinate if it is suicidal or violates superko
-      if (isSuicidal > 0 || history.violatesSuperko(newState)) return;
+      if (isSuicidal > 0 || history.violatesKoRule(newState)) return;
 
       // update leelaz with board position
       if (Lizzie.frame.isPlayingAgainstLeelaz

diff --git a/src/main/java/featurecat/lizzie/rules/BoardHistoryList.java b/src/main/java/featurecat/lizzie/rules/BoardHistoryList.java
@@ -190,6 +190,12 @@ public boolean violatesSuperko(BoardData data) {
     return false;
   }
 
+  public boolean violatesKoRule(BoardData data) {
+    BoardHistoryNode previous = this.head.previous();
+    // check if the current position is identical to the position two moves ago
+    return previous != null && data.zobrist.equals(previous.getData().zobrist);
+  }
+
   /**
    * Returns the root node
    *