v0.6

Author: aniketshedge-packt

Lesson03/Activity02/Activity2.cpp

@@ -0,0 +1,77 @@
+#include <iostream>
+#include <vector>
+
+#include <openssl/md5.h>
+
+class BloomFilter
+{
+    int nHashes;
+    std::vector<bool> bits;
+
+    static constexpr int hashSize = 128 / 8;
+
+    unsigned char hashValue[hashSize];
+
+public:
+    BloomFilter(int size, int hashes) : bits(size), nHashes(hashes)
+    {
+        if (nHashes > hashSize)
+        {
+            throw("Number of hash functions too high");
+        }
+
+        if (size > 255)
+        {
+            throw("Size of bloom filter can't be >255");
+        }
+    }
+
+    void hash(const std::string &key)
+    {
+        MD5(reinterpret_cast<const unsigned char *>(key.data()), key.length(), hashValue);
+    }
+
+    void add(const std::string &key)
+    {
+        hash(key);
+        for (auto it = &hashValue[0]; it < &hashValue[nHashes]; it++)
+        {
+            bits[*it] = true;
+        }
+        std::cout << key << " added in bloom filter." << std::endl;
+    }
+
+    bool mayContain(const std::string &key)
+    {
+        hash(key);
+        for (auto it = &hashValue[0]; it < &hashValue[nHashes]; it++)
+        {
+            if (!bits[*it])
+            {
+                std::cout << key << " email can by used." << std::endl;
+                return false;
+            }
+        }
+
+        std::cout << key << " email is used by someone else." << std::endl;
+        return true;
+    }
+};
+
+int main()
+{
+    BloomFilter bloom(10, 15);
+
+    bloom.add("[email protected]");
+    bloom.add("[email protected]");
+
+    bloom.mayContain("abc");
+    bloom.mayContain("[email protected]");
+    bloom.mayContain("xyz");
+
+    bloom.add("[email protected]");
+    bloom.add("[email protected]");
+
+    bloom.mayContain("abcd");
+    bloom.mayContain("[email protected]");
+}

Lesson03/Exercise01/1.cpp

@@ -38,7 +38,7 @@ class hash_map
 
 int main()
 {
-    hash_map map(100); // Let’s go with 100 as its easier for calculation.
+    hash_map map(7);
 
     auto print = [&](int value) {
         if (map.find(value))
@@ -48,22 +48,14 @@ int main()
         std::cout << std::endl;
     };
 
-    map.insert(3135); // Inserts at position 35
-    map.insert(3);    // Inserts at position 3
-    map.insert(34);   // Inserts at position 34
+    map.insert(2);
+    map.insert(25);
+    map.insert(290);
 
-    print(35);
-    print(34);
-    print(10);
-
-    map.insert(55);
-    map.erase(155);
-    print(55);
-    map.erase(55);
-    print(55);
+    print(25);
+    print(100);
 
     map.insert(100);
-    map.insert(0);
-    print(0);
     print(100);
+    map.erase(25);
 }

Lesson03/Exercise02/2.cpp

@@ -44,7 +44,7 @@ class hash_map
 
 int main()
 {
-    hash_map map(100); // Let’s go with 100 as its easier for calculation.
+    hash_map map(7);
 
     auto print = [&](int value) {
         if (map.find(value))
@@ -54,22 +54,13 @@ int main()
         std::cout << std::endl;
     };
 
-    map.insert(3135); // Inserts at position 35
-    map.insert(3);    // Inserts at position 3
-    map.insert(34);   // Inserts at position 34
-
-    print(35);
-    print(34);
-    print(10);
+    map.insert(2);
+    map.insert(25);
+    map.insert(290);
 
+    map.insert(100);
     map.insert(55);
-    map.erase(155);
-    print(55);
-    map.erase(55);
-    print(55);
 
-    map.insert(100);
-    map.insert(0);
-    print(0);
     print(100);
+    map.erase(2);
 }