From 5ee48b459861014f0eae9e5b0ebed4096ae5d390 Mon Sep 17 00:00:00 2001
From: Didier Le Botlan <lebotlan@users.noreply.github.com>
Date: Tue, 29 Apr 2025 15:29:41 +0200
Subject: [PATCH] The recently added test on priorityqueue was not compatible
 with BinarySearchTree implementation. This is fixed.

---
 .../algorithm/utils/BinarySearchTree.java     | 43 ++++++++++++++++---
 .../algorithm/utils/PriorityQueueTest.java    | 16 +++++--
 2 files changed, 48 insertions(+), 11 deletions(-)

diff --git a/be-graphes-algos/src/main/java/org/insa/graphs/algorithm/utils/BinarySearchTree.java b/be-graphes-algos/src/main/java/org/insa/graphs/algorithm/utils/BinarySearchTree.java
index f711b30..1aa3284 100644
--- a/be-graphes-algos/src/main/java/org/insa/graphs/algorithm/utils/BinarySearchTree.java
+++ b/be-graphes-algos/src/main/java/org/insa/graphs/algorithm/utils/BinarySearchTree.java
@@ -1,18 +1,23 @@
 package org.insa.graphs.algorithm.utils;
 
-import java.util.SortedSet;
-import java.util.TreeSet;
+import java.util.*;
 
 public class BinarySearchTree<E extends Comparable<E>> implements PriorityQueue<E> {
 
     // Underlying implementation
-    private final SortedSet<E> sortedSet;
+
+    // Elements, sorted by their value
+    private SortedSet<E> sortedSet;
+
+    // Elements, by their hashcode.
+    private HashSet<E> elems;
 
     /**
      * Create a new empty binary search tree.
      */
     public BinarySearchTree() {
         this.sortedSet = new TreeSet<>();
+        this.elems = new HashSet<>();
     }
 
     /**
@@ -22,26 +27,50 @@ public class BinarySearchTree<E extends Comparable<E>> implements PriorityQueue<
      */
     public BinarySearchTree(BinarySearchTree<E> bst) {
         this.sortedSet = new TreeSet<>(bst.sortedSet);
+        this.elems = new HashSet<>(bst.elems);
     }
 
     @Override
     public boolean isEmpty() {
-        return sortedSet.isEmpty();
+        return this.sortedSet.isEmpty();
     }
 
     @Override
     public int size() {
-        return sortedSet.size();
+        return this.sortedSet.size();
     }
 
     @Override
     public void insert(E x) {
-        sortedSet.add(x);
+        this.sortedSet.add(x);
+        this.elems.add(x);
     }
 
     @Override
     public void remove(E x) throws ElementNotFoundException {
-        if (!sortedSet.remove(x)) {
+
+        if (this.elems.contains(x)) {
+            // x is known to be here.
+
+            boolean removed = this.sortedSet.remove(x) ;
+            this.elems.remove(x) ;
+
+            if (!removed) {
+                // The element x was not found in the sorted tree, because its value has changed.
+                // However, we know it is here.
+
+                // This forces the sorted set to be reorganized
+                SortedSet<E> ts = this.sortedSet ;
+                this.sortedSet = new TreeSet<>() ;
+                for (E y : ts) {
+                    this.sortedSet.add(y) ;
+                }
+
+                removed = this.sortedSet.remove(x) ;
+                assert(removed) ;
+            }
+        }
+        else {
             throw new ElementNotFoundException(x);
         }
     }
diff --git a/be-graphes-algos/src/test/java/org/insa/graphs/algorithm/utils/PriorityQueueTest.java b/be-graphes-algos/src/test/java/org/insa/graphs/algorithm/utils/PriorityQueueTest.java
index 27bb14e..aca7b79 100644
--- a/be-graphes-algos/src/test/java/org/insa/graphs/algorithm/utils/PriorityQueueTest.java
+++ b/be-graphes-algos/src/test/java/org/insa/graphs/algorithm/utils/PriorityQueueTest.java
@@ -43,10 +43,16 @@ public abstract class PriorityQueueTest {
     protected static class MutableInteger implements Comparable<MutableInteger> {
 
         // Actual value
-        private int value;
+        private int value ;
+
+        // Unique identifier, used to get a hashcode that does not depend on the value (which may change)
+        private int id ;
+
+        private static int counter = 1000 ;
 
         public MutableInteger(int value) {
-            this.value = value;
+            this.value = value ;
+            this.id = counter++ ;
         }
 
         /**
@@ -67,12 +73,13 @@ public abstract class PriorityQueueTest {
 
         @Override
         public int compareTo(MutableInteger other) {
-            return Integer.compare(this.value, other.value);
+            if (this.id == other.id) return 0 ;
+            else return Integer.compare(this.value, other.value);
         }
 
         @Override
         public String toString() {
-            return Integer.toString(get());
+            return "" + this.get() + " [id:" + this.id + "]";
         }
 
     };
@@ -314,6 +321,7 @@ public abstract class PriorityQueueTest {
             // Update value before removing it. This is what happens when updating a Dijkstra label before updating it.
             mi.set(--min);
             queue.remove(mi);
+            
             assertEquals(parameters.data.length - 1, queue.size());
             queue.insert(mi);
             assertEquals(parameters.data.length, queue.size());