diff --git a/hashing/quadratic_probing_hash_table.cpp b/hashing/quadratic_probing_hash_table.cpp index ac779eed5..5b7038637 100644 --- a/hashing/quadratic_probing_hash_table.cpp +++ b/hashing/quadratic_probing_hash_table.cpp @@ -10,8 +10,14 @@ #include #include -namespace { // keep the code local to this file by assigning them to an unnamed - +/** + * @addtogroup Open Addressing + * @{ + * @namespace quadratic_probing + * @brief An implementation of hash table using [quadratic + * probing](https://en.wikipedia.org/wiki/Quadratic_probing) algorithm. + */ +namespace quadratic_probing { // fwd declarations using Entry = struct Entry; bool putProber(const Entry& entry, int key); @@ -26,19 +32,27 @@ int tomb = -1; int size; bool rehashing; -// Node that holds key +/** Node that holds key + */ struct Entry { - explicit Entry(int key = notPresent) : key(key) {} - int key; + explicit Entry(int key = notPresent) : key(key) {} ///< constructor + int key; ///< key value }; -// Hash a key +/** Hash a key + * @param key key value to hash + * @returns hash of the key + */ size_t hashFxn(int key) { std::hash hash; return hash(key); } -// Performs quadratic probing to resolve collisions +/** Performs quadratic probing to resolve collisions + * @param key key value to search/probe + * @param searching `true` if only searching, `false1 if assigning + * @returns value of `notPresent`. + */ int quadraticProbe(int key, bool searching) { int hash = static_cast(hashFxn(key)); int i = 0; @@ -83,7 +97,12 @@ int quadraticProbe(int key, bool searching) { return notPresent; } -// Finds empty spot +/** Finds empty spot + * @param entry Instance of table entry + * @param key key value to search/probe + * @returns `true` if key is present + * @returns `false` if key is absent + */ bool putProber(const Entry& entry, int key) { if (entry.key == notPresent || entry.key == tomb) { return true; @@ -91,7 +110,12 @@ bool putProber(const Entry& entry, int key) { return false; } -// Looks for a matching key +/** Looks for a matching key + * @param entry Instance of table entry + * @param key key value to search/probe + * @returns `true` if key matches the entry + * @returns `false` if key does not match the entry + */ bool searchingProber(const Entry& entry, int key) { if (entry.key == key) { return true; @@ -99,7 +123,11 @@ bool searchingProber(const Entry& entry, int key) { return false; } -// Helper +/** Get the entry instance corresponding to a key + * @param key key value to search/probe + * @returns if present, the entry instance + * @returns if not present, a new instance + */ Entry find(int key) { int index = quadraticProbe(key, true); if (index == notPresent) { @@ -108,7 +136,9 @@ Entry find(int key) { return table[index]; } -// Displays the table +/** Displays the table + * @returns None + */ void display() { for (int i = 0; i < totalSize; i++) { if (table[i].key == notPresent) { @@ -124,7 +154,9 @@ void display() { std::cout << std::endl; } -// Rehashes the table into a bigger table +/** Rehashes the table into a bigger table + * @returns none + */ void rehash() { // Necessary so wall of add info isn't printed all at once rehashing = true; @@ -144,7 +176,9 @@ void rehash() { std::cout << "Table was rehashed, new size is: " << totalSize << std::endl; } -// Checks for load factor here +/** Checks for load factor here + * @param key key value to hash and add to table + */ void add(int key) { int index = quadraticProbe(key, false); table[index].key = key; @@ -154,7 +188,9 @@ void add(int key) { } } -// Removes key. Leaves tombstone upon removal. +/** Removes key. Leaves tombstone upon removal. + * @param key key value to hash and remove from table + */ void remove(int key) { int index = quadraticProbe(key, true); if (index == notPresent) { @@ -165,7 +201,9 @@ void remove(int key) { size--; } -// Information about the adding process +/** Information about the adding process + * @param key key value to hash and add to table + */ void addInfo(int key) { std::cout << "Initial table: "; display(); @@ -178,7 +216,9 @@ void addInfo(int key) { display(); } -// Information about removal process +/** Information about removal process + * @param key key value to hash and remove from table + */ void removalInfo(int key) { std::cout << "Initial table: "; display(); @@ -190,9 +230,19 @@ void removalInfo(int key) { std::cout << "New table: "; display(); } -} // namespace -// I/O +} // namespace quadratic_probing +/** + * @} + */ + +using quadratic_probing::Entry; +using quadratic_probing::table; +using quadratic_probing::totalSize; + +/** Main function + * @returns None + */ int main() { int cmd = 0, hash = 0, key = 0; std::cout << "Enter the initial size of Hash Table. = "; @@ -214,18 +264,20 @@ int main() { case 1: std::cout << "Enter key to add = "; std::cin >> key; - addInfo(key); + quadratic_probing::addInfo(key); break; case 2: std::cout << "Enter key to remove = "; std::cin >> key; - removalInfo(key); + quadratic_probing::removalInfo(key); break; case 3: { std::cout << "Enter key to search = "; std::cin >> key; - Entry entry = table[quadraticProbe(key, true)]; - if (entry.key == notPresent) { + quadratic_probing::Entry entry = + quadratic_probing::table[quadratic_probing::quadraticProbe( + key, true)]; + if (entry.key == quadratic_probing::notPresent) { std::cout << "Key not present"; } break; @@ -233,10 +285,11 @@ int main() { case 4: std::cout << "Enter element to generate hash = "; std::cin >> key; - std::cout << "Hash of " << key << " is = " << hashFxn(key); + std::cout << "Hash of " << key + << " is = " << quadratic_probing::hashFxn(key); break; case 5: - display(); + quadratic_probing::display(); break; default: loop = false;