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Merged
merged 2 commits into from
May 4, 2022
Merged

Create BloomFilter #3042

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53cfce6
Create BloomFilter
omarmahamid May 4, 2022
bc87bd7
private hash
omarmahamid May 4, 2022
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59 changes: 59 additions & 0 deletions src/main/java/com/thealgorithms/datastructures/bloomfilter/BloomFilter.java
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Original file line number Diff line number Diff line change
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package com.thealgorithms.datastructures.bloomfilter;


public class BloomFilter<T> {

private int numberOfHashFunctions;
private int [] bitArray;
private Hash<T>[] hashFunctions;

public BloomFilter(int numberOfHashFunctions, int n) {
this.numberOfHashFunctions = numberOfHashFunctions;
hashFunctions = new Hash[numberOfHashFunctions];
bitArray = new int[n];
insertHash();
}

private void insertHash() {
for (int i = 0; i < numberOfHashFunctions; i++) {
hashFunctions[i] = new Hash(i);
}
}

public void insert(T key) {
for (Hash<T> hash : hashFunctions){
bitArray[hash.compute(key) % bitArray.length] = 1;
}
}

public boolean contains(T key) {
for (Hash<T> hash : hashFunctions){
if (bitArray[hash.compute(key) % bitArray.length] == 0){
return false;
}
}
return true;
}

private class Hash<T> {

int index;

public Hash(int index){
this.index = index;
}

public int compute(T key){
return index * asciiString(String.valueOf(key));
}

private int asciiString(String word){
int number = 0;
for (int i=0;i<word.length();i++){
number += word.charAt(i);
}
return number;
}
}

}
28 changes: 28 additions & 0 deletions src/test/java/com/thealgorithms/datastructures/BloomFilterTest.java
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package com.thealgorithms.datastructures.bloomfilter;

import org.junit.jupiter.api.Assertions;
import org.junit.jupiter.api.Test;


public class BloomFilterTest {

@Test
public void test1(){
BloomFilter<Integer> bloomFilter = new BloomFilter<>(3,10);
bloomFilter.insert(3);
bloomFilter.insert(17);

Assertions.assertTrue(bloomFilter.contains(3));
Assertions.assertTrue(bloomFilter.contains(17));
}

@Test
public void test2(){
BloomFilter<String> bloomFilter = new BloomFilter<>(4,20);
bloomFilter.insert("omar");
bloomFilter.insert("mahamid");

Assertions.assertTrue(bloomFilter.contains("omar"));
Assertions.assertTrue(bloomFilter.contains("mahamid"));
}
}