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uebung_03: implement Task 3 (BST) and Task 4 (IntHashSet)

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Task 3 adds IntBinarySearchTree with iterative add/contains and a
test class covering empty trees, duplicates, and degenerate ascending
and descending insertion orders.

Task 4 adds IntHashSet backed by an IntLinkedList bucket array with
a 0.7 load factor, Math.floorMod-based hashing for negative-int
safety, doubling resize that rehashes via a private
addWithoutResize helper, and a test class covering negatives,
Integer.MIN_VALUE, forced collisions on bucket 0, and 100-element
inserts spanning three resizes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
This commit is contained in:
Jean-Luc Makiola
2026-05-23 23:19:48 +02:00
parent 964e6a0afb
commit 9b6528d800
5 changed files with 317 additions and 0 deletions
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54
uebung_03/src/IntBinarySearchTree.java Normal file
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public class IntBinarySearchTree {
IntTreeNode root;
public IntBinarySearchTree(){
}
public void add(int value){
if (root == null){
root = new IntTreeNode(value);
return;
}
IntTreeNode currentRelativRoot = root;
while (true) {
if(value == currentRelativRoot.value){
return;
}
if (value < currentRelativRoot.value) {
if (currentRelativRoot.left == null) {
currentRelativRoot.left = new IntTreeNode(value);
return;
} else currentRelativRoot = currentRelativRoot.left;
} else {
if (currentRelativRoot.right == null) {
currentRelativRoot.right = new IntTreeNode(value);
return;
} else currentRelativRoot = currentRelativRoot.right;
}
}
}
public boolean contains(int value){
if (root == null) return false;
IntTreeNode currentRelativRoot = root;
while (true){
if(value == currentRelativRoot.value){
return true;
}
if (value < currentRelativRoot.value) {
if (currentRelativRoot.left == null) {
return false;
} else currentRelativRoot = currentRelativRoot.left;
} else {
if (currentRelativRoot.right == null) {
return false;
} else currentRelativRoot = currentRelativRoot.right;
}
}
}
}

96
uebung_03/src/IntBinarySearchTreeTest.java Normal file
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public class IntBinarySearchTreeTest {
static int passed = 0;
static int failed = 0;
public static void main(String[] args) {
testEmptyContains();
testSingleAdd();
testStandardTree();
testDuplicate();
testLeftAndRightExtremes();
testStrictlyAscending();
testStrictlyDescending();
System.out.println();
System.out.println("Passed: " + passed + " / " + (passed + failed));
}
static void testEmptyContains() {
IntBinarySearchTree t = new IntBinarySearchTree();
checkBool("empty contains(5)", t.contains(5), false);
}
static void testSingleAdd() {
IntBinarySearchTree t = new IntBinarySearchTree();
t.add(42);
checkBool("single contains(42)", t.contains(42), true);
checkBool("single contains(7)", t.contains(7), false);
}
static void testStandardTree() {
IntBinarySearchTree t = new IntBinarySearchTree();
int[] vals = {5, 3, 8, 1, 4, 7, 9, 5};
for (int v : vals) t.add(v);
checkBool("contains(7)", t.contains(7), true);
checkBool("contains(6)", t.contains(6), false);
checkBool("contains(1)", t.contains(1), true);
checkBool("contains(9)", t.contains(9), true);
checkBool("contains(5)", t.contains(5), true);
checkBool("contains(4)", t.contains(4), true);
checkBool("contains(3)", t.contains(3), true);
checkBool("contains(0)", t.contains(0), false);
checkBool("contains(10)", t.contains(10), false);
}
static void testDuplicate() {
IntBinarySearchTree t = new IntBinarySearchTree();
t.add(10);
t.add(10);
t.add(10);
checkBool("duplicates contains(10)", t.contains(10), true);
// Tree should still work after duplicates
t.add(5);
t.add(15);
checkBool("after dup contains(5)", t.contains(5), true);
checkBool("after dup contains(15)", t.contains(15), true);
}
static void testLeftAndRightExtremes() {
IntBinarySearchTree t = new IntBinarySearchTree();
int[] vals = {50, 25, 75, 10, 35, 60, 90, 5, 15, 30, 40};
for (int v : vals) t.add(v);
for (int v : vals) checkBool("extremes contains(" + v + ")", t.contains(v), true);
checkBool("extremes contains(-1)", t.contains(-1), false);
checkBool("extremes contains(100)", t.contains(100), false);
checkBool("extremes contains(45)", t.contains(45), false);
}
static void testStrictlyAscending() {
// Degenerates into a right-only chain - good edge case
IntBinarySearchTree t = new IntBinarySearchTree();
for (int i = 1; i <= 10; i++) t.add(i);
for (int i = 1; i <= 10; i++) checkBool("asc contains(" + i + ")", t.contains(i), true);
checkBool("asc contains(0)", t.contains(0), false);
checkBool("asc contains(11)", t.contains(11), false);
}
static void testStrictlyDescending() {
// Degenerates into a left-only chain
IntBinarySearchTree t = new IntBinarySearchTree();
for (int i = 10; i >= 1; i--) t.add(i);
for (int i = 1; i <= 10; i++) checkBool("desc contains(" + i + ")", t.contains(i), true);
checkBool("desc contains(0)", t.contains(0), false);
checkBool("desc contains(11)", t.contains(11), false);
}
static void checkBool(String label, boolean actual, boolean expected) {
if (actual == expected) {
System.out.println("PASS " + label + " = " + actual);
passed++;
} else {
System.out.println("FAIL " + label + " expected=" + expected + " actual=" + actual);
failed++;
}
}
}

81
uebung_03/src/IntHashSet.java Normal file
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public class IntHashSet {
private IntLinkedList[] buckets;
private int size;
private int capacity;
private static final double LOAD_PERCENT = 0.7;
public IntHashSet(){
buckets = new IntLinkedList[16];
capacity = 16;
}
private int hash(int value){
return Math.floorMod(value, capacity);
}
private boolean loadReached(){
return (double) size / capacity >= LOAD_PERCENT;
}
private void resize(){
IntLinkedList[] oldBuckets = buckets;
capacity *=2;
buckets = new IntLinkedList[capacity];
size = 0;
for (IntLinkedList oldBucket : oldBuckets) {
if (oldBucket == null) continue;
for (int j = 0; j < oldBucket.getSize(); j++) {
addWithoutResize(oldBucket.get(j));
}
}
}
public void add(int value){
int index = hash(value);
if (buckets[index] == null){
buckets[index] = new IntLinkedList();
buckets[index].add(value);
size++;
if (loadReached()) resize();
return;
}
for (int i = 0; i < buckets[index].getSize(); i++){
if (buckets[index].get(i) == value){
return;
}
}
buckets[index].add(value);
size++;
if (loadReached()) resize();
}
private void addWithoutResize(int value){
int index = hash(value);
if (buckets[index] == null){
buckets[index] = new IntLinkedList();
buckets[index].add(value);
size++;
return;
}
for (int i = 0; i < buckets[index].getSize(); i++){
if (buckets[index].get(i) == value){
return;
}
}
buckets[index].add(value);
size++;
}
public boolean contains(int value){
int index = hash(value);
if (buckets[index] == null){
return false;
}
for (int i = 0; i < buckets[index].getSize(); i++){
if (buckets[index].get(i) == value){
return true;
}
}
return false;
}
}

74
uebung_03/src/IntHashSetTest.java Normal file
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public class IntHashSetTest {
static int passed = 0, failed = 0;
public static void main(String[] args) {
testEmpty();
testAddContains();
testDuplicates();
testNegatives();
testManyForcingResize();
testCollisions();
System.out.println();
System.out.println("Passed: " + passed + " / " + (passed + failed));
}
static void testEmpty() {
IntHashSet s = new IntHashSet();
checkBool("empty contains(5)", s.contains(5), false);
checkBool("empty contains(-1)", s.contains(-1), false);
checkBool("empty contains(0)", s.contains(0), false);
}
static void testAddContains() {
IntHashSet s = new IntHashSet();
s.add(1); s.add(2); s.add(3);
checkBool("contains(1)", s.contains(1), true);
checkBool("contains(2)", s.contains(2), true);
checkBool("contains(3)", s.contains(3), true);
checkBool("contains(4)", s.contains(4), false);
}
static void testDuplicates() {
IntHashSet s = new IntHashSet();
s.add(7); s.add(7); s.add(7); s.add(7);
checkBool("dup contains(7)", s.contains(7), true);
// no easy way to inspect size without exposing it; trust it
}
static void testNegatives() {
IntHashSet s = new IntHashSet();
s.add(-1); s.add(-100); s.add(Integer.MIN_VALUE);
checkBool("contains(-1)", s.contains(-1), true);
checkBool("contains(-100)", s.contains(-100), true);
checkBool("contains(MIN_VALUE)", s.contains(Integer.MIN_VALUE), true);
checkBool("contains(1) after negs", s.contains(1), false);
}
static void testManyForcingResize() {
// Insert 100 values - capacity starts at 16, will resize multiple times
IntHashSet s = new IntHashSet();
for (int i = 0; i < 100; i++) s.add(i);
for (int i = 0; i < 100; i++) {
checkBool("post-resize contains(" + i + ")", s.contains(i), true);
}
checkBool("post-resize contains(100)", s.contains(100), false);
checkBool("post-resize contains(-1)", s.contains(-1), false);
}
static void testCollisions() {
// Values that all hash to bucket 0 in capacity 16 (multiples of 16)
IntHashSet s = new IntHashSet();
s.add(0); s.add(16); s.add(32); s.add(48);
checkBool("collision contains(0)", s.contains(0), true);
checkBool("collision contains(16)", s.contains(16), true);
checkBool("collision contains(32)", s.contains(32), true);
checkBool("collision contains(48)", s.contains(48), true);
checkBool("collision contains(8)", s.contains(8), false);
checkBool("collision contains(64)", s.contains(64), false);
}
static void checkBool(String label, boolean actual, boolean expected) {
if (actual == expected) { System.out.println("PASS " + label + " = " + actual); passed++; }
else { System.out.println("FAIL " + label + " expected=" + expected + " actual=" + actual); failed++; }
}
}

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uebung_03/src/IntTreeNode.java Normal file
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public class IntTreeNode {
int value;
IntTreeNode left;
IntTreeNode right;
public IntTreeNode(int value){
this.value = value;
}
}