From 93628f9b4eccfd2a1b629c573e7c499160e6f788 Mon Sep 17 00:00:00 2001
From: mike <michael@appmodel.nl>
Date: Mon, 12 Jan 2026 04:27:46 +0100
Subject: [PATCH] introduce bitloops

---
 src/main/java/puzzle/SwedishGenerator.java | 91 ++++++++++++++++++----
 1 file changed, 74 insertions(+), 17 deletions(-)

diff --git a/src/main/java/puzzle/SwedishGenerator.java b/src/main/java/puzzle/SwedishGenerator.java
index 7afbe5c..bcc5f9c 100644
--- a/src/main/java/puzzle/SwedishGenerator.java
+++ b/src/main/java/puzzle/SwedishGenerator.java
@@ -70,18 +70,19 @@ public record SwedishGenerator(Rng rng) {
    static int clamp(int x, int a, int b) { return Math.max(a, Math.min(b, x)); }
    record Pick(Slot slot, CandidateInfo info, boolean done) { }
    
-   static final byte      B0            = (byte) 0;
-   static final byte      B64           = (byte) 64;
-   static final byte      B48           = (byte) 48;
+   static final byte      B0             = (byte) 0;
+   static final byte      B64            = (byte) 64;
+   static final byte      B48            = (byte) 48;
    // Directions for '1'..'6'
-   static final nbrs_16[] OFFSETS       = Neighbors9x8.OFFSETS;
-   static final nbrs_16[] OFFSETS_FOUR  = Neighbors9x8.OFFSETS_FOUR;
-   static final nbrs_8[]  nbrs8         = Neighbors9x8.nbrs8;
-   static final nbrs_8[]  nbrs4         = Neighbors9x8.nbrs4;
-   static final rci[]     IT            = Neighbors9x8.IT;
-   static final long[]    INBR8_PACKEDT = Neighbors9x8.NBR8_PACKED;
-   static final int[][]   MUTATE_RI     = new int[SIZE][625];
-   static final long[]    NBR8_PACKED   = Neighbors9x8.NBR8_PACKED;
+   static final nbrs_16[] OFFSETS        = Neighbors9x8.OFFSETS;
+   static final nbrs_16[] OFFSETS_FOUR   = Neighbors9x8.OFFSETS_FOUR;
+   static final nbrs_8[]  nbrs8          = Neighbors9x8.nbrs8;
+   static final nbrs_8[]  nbrs4          = Neighbors9x8.nbrs4;
+   static final rci[]     IT             = Neighbors9x8.IT;
+   static final long[]    INBR8_PACKEDT  = Neighbors9x8.NBR8_PACKED;
+   static final int[][]   MUTATE_RI      = new int[SIZE][625];
+   static final long[]    NBR8_PACKED_LO = Neighbors9x8.NBR8_PACKED_LO;
+   static final long[]    NBR8_PACKED_HI = Neighbors9x8.NBR8_PACKED_HI;
    
    static {
       for (int i = 0; i < SIZE; i++) {
@@ -441,11 +442,67 @@ public record SwedishGenerator(Rng rng) {
       
       if (!hasSlots) return 1_000_000_000L;
       
-      var seen  = ctx.seen;
-      var stack = ctx.stack;
-      seen.clear();
-      
-      for (int i = 0; i < 65; i += 64) {
+      var  stack  = ctx.stack;
+      long seenLo = 0L, seenHi = 0L;
+
+// loop over beide helften
+      for (int base = 0; base <= 64; base += 64) {
+         long clueMask = (base == 0) ? lo_cl : hi_cl;
+         long seenMask = (base == 0) ? seenLo : seenHi;
+         
+         // "unseen clues" in deze helft
+         for (long bits = clueMask & ~seenMask; bits != 0L; bits &= bits - 1) {
+            int clueIdx = base + Long.numberOfTrailingZeros(bits);
+            
+            // start nieuwe component
+            int size = 0;
+            int sp   = 0;
+            stack[sp++] = clueIdx;
+            
+            // mark seen
+            if (clueIdx < 64) seenLo |= 1L << clueIdx;
+            else seenHi |= 1L << (clueIdx - 64);
+            
+            // flood fill / bfs
+            while (sp > 0) {
+               int cur = stack[--sp];
+               size++;
+               
+               // neighbors als 2x long masks
+               long nLo = NBR8_PACKED_LO[cur];
+               long nHi = NBR8_PACKED_HI[cur];
+               
+               // filter: alleen clues, en nog niet seen
+               nLo &= lo_cl & ~seenLo;
+               nHi &= hi_cl & ~seenHi;
+               
+               // push lo-neighbors
+               while (nLo != 0L) {
+                  long lsb  = nLo & -nLo;
+                  int  nidx = Long.numberOfTrailingZeros(nLo); // 0..63
+                  seenLo |= lsb;
+                  
+                  stack[sp++] = nidx;
+                  
+                  nLo &= nLo - 1;
+               }
+               
+               // push hi-neighbors
+               while (nHi != 0L) {
+                  long lsb  = nHi & -nHi;
+                  int  nidx = 64 + Long.numberOfTrailingZeros(nHi); // 64..127
+                  seenHi |= lsb;
+                  
+                  stack[sp++] = nidx;
+                  
+                  nHi &= nHi - 1;
+               }
+            }
+            
+            if (size >= 2) penalty += (size - 1L) * 120L;
+         }
+      }
+      /*for (int i = 0; i < 65; i += 64) {
          for (long bits = (i == 0 ? lo_cl : hi_cl); bits != X; bits &= bits - 1) {
             int clueIdx = i + Long.numberOfTrailingZeros(bits);
             if (seen.get(clueIdx)) continue;
@@ -463,7 +520,7 @@ public record SwedishGenerator(Rng rng) {
             }
             if (size >= 2) penalty += ((size - 1L) * 120L);
          }
-      }
+      }*/
       
       for (int i = 0; i < 65; i += 64) {
          long bits = (i == 0 ? ~lo_cl : (~hi_cl & 0xFFL));