From c78d3d9023645a7e7042fa6e69ff4645efc9fb7c Mon Sep 17 00:00:00 2001
From: Arthur Godet <arth.godet@gmail.com>
Date: Tue, 12 Nov 2024 10:39:05 +0100
Subject: [PATCH] Fix bin packing initial propagation (#1113)

* #1112 : fix bin packing initial propagation

* move code initialising P and sumP from constructor to fullPropagation in PropBinPacking

* clear R and P sets before full propagation in PropBinPacking
---
 .../nary/binPacking/PropBinPacking.java       | 33 +++++++++++--------
 .../constraints/nary/BinPackingTest.java      | 26 +++++++++++++++
 2 files changed, 45 insertions(+), 14 deletions(-)

diff --git a/solver/src/main/java/org/chocosolver/solver/constraints/nary/binPacking/PropBinPacking.java b/solver/src/main/java/org/chocosolver/solver/constraints/nary/binPacking/PropBinPacking.java
index 639ff6d233..6e54938dfb 100644
--- a/solver/src/main/java/org/chocosolver/solver/constraints/nary/binPacking/PropBinPacking.java
+++ b/solver/src/main/java/org/chocosolver/solver/constraints/nary/binPacking/PropBinPacking.java
@@ -127,20 +127,8 @@ public PropBinPacking(IntVar[] itemBin, int[] itemSize, IntVar[] binLoad, int of
         for(int j = 0; j<nbAvailableBins; j++) {
             P[j] = SetFactory.makeStoredSet(SetType.BITSET, 0, itemBin[0].getModel());
             R[j] = SetFactory.makeStoredSet(SetType.BITSET, 0, itemBin[0].getModel());
-            int pj = 0;
-            int rj = 0;
-            for(int i = 0; i<nbItems; i++) {
-                if(itemBin[i].contains(j+offset)) {
-                    P[j].add(i);
-                    pj += itemSize[i];
-                    if(itemBin[i].isInstantiated()) {
-                        R[j].add(i);
-                        rj += itemSize[i];
-                    }
-                }
-            }
-            sumR[j] = itemBin[0].getModel().getEnvironment().makeInt(rj);
-            sumP[j] = itemBin[0].getModel().getEnvironment().makeInt(pj);
+            sumR[j] = itemBin[0].getModel().getEnvironment().makeInt(0);
+            sumP[j] = itemBin[0].getModel().getEnvironment().makeInt(0);
         }
 
         binsToProcess = new BitSet(nbAvailableBins);
@@ -345,9 +333,26 @@ public void propagate(int idxVarInProp, int mask) throws ContradictionException
         forcePropagate(PropagatorEventType.CUSTOM_PROPAGATION);
     }
 
+    private void initializeBinsDataStructure() {
+        for(int j = 0; j<nbAvailableBins; j++) {
+            R[j].clear();
+            P[j].clear();
+            sumR[j].set(0);
+            int pj = 0;
+            for (int i = 0; i < nbItems; i++) {
+                if (itemBin[i].contains(j + offset)) {
+                    P[j].add(i);
+                    pj += itemSize[i];
+                }
+            }
+            sumP[j].set(pj);
+        }
+    }
+
     @Override
     public void propagate(int evtmask) throws ContradictionException {
         if(PropagatorEventType.isFullPropagation(evtmask)) {
+            initializeBinsDataStructure();
             for(int i = 0; i<itemBin.length; i++) { // Pack All
                 itemBin[i].updateBounds(offset, nbAvailableBins+offset-1, this);
                 if(itemBin[i].isInstantiated()) {
diff --git a/solver/src/test/java/org/chocosolver/solver/constraints/nary/BinPackingTest.java b/solver/src/test/java/org/chocosolver/solver/constraints/nary/BinPackingTest.java
index 27de7f07ed..2752da550a 100644
--- a/solver/src/test/java/org/chocosolver/solver/constraints/nary/BinPackingTest.java
+++ b/solver/src/test/java/org/chocosolver/solver/constraints/nary/BinPackingTest.java
@@ -11,6 +11,7 @@
 
 import org.chocosolver.solver.Cause;
 import org.chocosolver.solver.Model;
+import org.chocosolver.solver.Solver;
 import org.chocosolver.solver.constraints.Constraint;
 import org.chocosolver.solver.constraints.ConstraintsName;
 import org.chocosolver.solver.constraints.nary.binPacking.PropBinPacking;
@@ -18,6 +19,9 @@
 import org.chocosolver.solver.search.strategy.Search;
 import org.chocosolver.solver.variables.BoolVar;
 import org.chocosolver.solver.variables.IntVar;
+import org.chocosolver.solver.variables.impl.BitsetIntVarImpl;
+import org.chocosolver.solver.variables.impl.BoolVarImpl;
+import org.chocosolver.util.ESat;
 import org.chocosolver.util.tools.ArrayUtils;
 import org.testng.Assert;
 import org.testng.annotations.DataProvider;
@@ -157,4 +161,26 @@ public void testFixedLoadBackPropag2() {
 		model.getSolver().findAllSolutions();
 		Assert.assertEquals(model.getSolver().getSolutionCount(), 16);
 	}
+
+	@Test(groups = "1s", timeOut = 60000)
+	public void testBug1() {
+		Model model = new Model();
+		int[] itemSize = new int[]{2, 9};
+		IntVar[] itemBin = new IntVar[2];
+		itemBin[0] = new BitsetIntVarImpl("X_0", new int[]{0, 1}, model);
+		itemBin[1] = new BitsetIntVarImpl("X_1", new int[]{0}, model);
+		IntVar[] binLoad = new IntVar[2];
+		binLoad[0] = new BoolVarImpl("X_6", model);
+		binLoad[1] = new BitsetIntVarImpl("X_8", new int[]{0, 9, 11}, model);
+		Constraint c = model.binPacking(itemBin, itemSize, binLoad, 0);
+		c.post();
+		Assert.assertEquals(c.isSatisfied(), ESat.FALSE);
+		Solver solver = model.getSolver();
+		try {
+			solver.propagate();
+			Assert.fail();
+		} catch (ContradictionException e) {
+			// should fail
+		}
+	}
 }