Java
package leetcode.template;
import java.util.BitSet;
public class BloomFilter {
private static final int DEFAULT_SIZE = 2 << 24;
private static final int[] seeds = new int[]{5, 7, 11, 13, 31, 37, 61};
private BitSet bits = new BitSet(DEFAULT_SIZE);
private SimpleHash[] func = new SimpleHash[seeds.length];
public BloomFilter() {
for (int i = 0; i < seeds.length; i++) {
func[i] = new SimpleHash(DEFAULT_SIZE, seeds[i]);
}
}
public void add(String value) {
for (SimpleHash f : func) {
bits.set(f.hash(value), true);
}
}
public boolean contains(String value) {
if (value == null) {
return false;
}
boolean ret = true;
for (SimpleHash f : func) {
ret = ret && bits.get(f.hash(value));
}
return ret;
}
public static class SimpleHash {
private int cap;
private int seed;
public SimpleHash(int cap, int seed) {
this.cap = cap;
this.seed = seed;
}
public int hash(String value) {
int result = 0;
int len = value.length();
for (int i = 0; i < len; i++) {
result = seed * result + value.charAt(i);
}
return (cap - 1) & result;
}
}
}
Python
from bitarray import bitarray
import mmh3
class BloomFilter:
def __init__(self, size, hash_num):
self.size = size
self.hash_num = hash_num
self.bit_array = bitarray(size)
self.bit_array.setall(0)
def add(self, s):
for seed in range(self.hash_num):
result = mmh3.hash(s, seed) % self.size
self.bit_array[result] = 1
def lookup(self, s):
for seed in range(self.hash_num):
result = mmh3.hash(s, seed) % self.size
if self.bit_array[result] == 0:
return "Nope"
return "Probably"
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