9.12 Lab: Hashing - Linear Probe (insert, search)

Hash Function: Add the ASCII values of all characters in the key string and return the reminder obtained when divided by the size of the table.

Example: If key = "Bob", and size = 53, we get (66 + 111 + 98) % 53 => 275 % 53 => 10.

Collision Resolution Method: Linear Probe.

The assignment consists of the following classes/files:

- main.cpp (incomplete)
- Student.h (given)
- HashNode.h (given)
- HashTable.h (given)
- HashTable.cpp (incomplete)

Read and understand the given code then write two functions:

- insert hash
- search hash

06-hash-tables/.idea/.gitignore

@@ -0,0 +1,8 @@
+# Default ignored files
+/shelf/
+/workspace.xml
+# Editor-based HTTP Client requests
+/httpRequests/
+# Datasource local storage ignored files
+/dataSources/
+/dataSources.local.xml

06-hash-tables/.idea/.name

@@ -0,0 +1 @@
+06_hash_tables

06-hash-tables/.idea/06-hash-tables.iml

@@ -0,0 +1,2 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module classpath="CMake" type="CPP_MODULE" version="4" />

06-hash-tables/.idea/inspectionProfiles/Project_Default.xml

@@ -0,0 +1,6 @@
+<component name="InspectionProjectProfileManager">
+  <profile version="1.0">
+    <option name="myName" value="Project Default" />
+    <inspection_tool class="Eslint" enabled="true" level="WARNING" enabled_by_default="true" />
+  </profile>
+</component>

06-hash-tables/.idea/misc.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="CMakeWorkspace" PROJECT_DIR="$PROJECT_DIR$" />
+</project>

06-hash-tables/.idea/modules.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectModuleManager">
+    <modules>
+      <module fileurl="file://$PROJECT_DIR$/.idea/06-hash-tables.iml" filepath="$PROJECT_DIR$/.idea/06-hash-tables.iml" />
+    </modules>
+  </component>
+</project>

06-hash-tables/.idea/vcs.xml

@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$/.." vcs="Git" />
+  </component>
+</project>

06-hash-tables/CMakeLists.txt

@@ -0,0 +1,7 @@
+cmake_minimum_required(VERSION 3.28)
+project(06_hash_tables)
+
+set(CMAKE_CXX_STANDARD 20)
+
+add_executable(06_hash_tables main.cpp
+        HashTable.cpp)

06-hash-tables/HashNode.h

@@ -0,0 +1,50 @@
+// Specification file for the HashNode class
+
+#ifndef _HASH_NODE
+#define _HASH_NODE
+
+#include "Student.h"
+
+using std::string;
+
+class HashNode {
+private:
+    Student item;
+    int occupied;   // 1 -> occupied, 0 -> empty 
+    int noCollisions;
+
+public:
+    // constructors
+    HashNode() {
+        occupied = 0;
+        noCollisions = 0;
+    }
+
+    HashNode(Student anItem) {
+        item = anItem;
+        occupied = 1;
+        noCollisions = 0;
+    }
+
+    HashNode(Student anItem, int ocp, int nCol) {
+        item = anItem;
+        occupied = ocp;
+        noCollisions = nCol;
+    }
+
+    // setters
+    void setItem(const Student &anItem) { item = anItem; }
+
+    void setOccupied(int ocp) { occupied = ocp; }
+
+    void setNoCollisions(int nCol) { noCollisions = nCol; }
+
+    // getters
+    Student getItem() const { return item; }
+
+    int getOccupied() const { return occupied; }
+
+    int getNoCollisions() const { return noCollisions; }
+};
+
+#endif

06-hash-tables/HashTable.cpp

@@ -0,0 +1,71 @@
+// Implementation file for the Hash class
+// Written By: Iurii Tatishchev
+// Changed by: Iurii Tatishchev
+
+#include <string>
+#include <utility>
+
+#include "HashTable.h"
+
+using namespace std;
+
+/*~*~*~*
+  A simple hash function 
+ *~**/
+int HashTable::_hash(string key) const {
+    int sum = 0;
+    for (char c : key)
+        sum += c;
+    return sum % hashSize;
+};
+
+/*~*~*~*
+  hash insert - linear probe
+*~**/
+bool HashTable::insert(const Student &itemIn) {
+    if (count == hashSize)
+        return false;
+    int pos = _hash(itemIn.getName());
+    int collisions = 0;
+    while (hashAry[pos].getOccupied()) {
+        ++pos;
+        ++collisions;
+        pos = pos % hashSize;
+    }
+    hashAry[pos].setItem(itemIn);
+    hashAry[pos].setOccupied(1);
+    hashAry[pos].setNoCollisions(collisions);
+    count++;
+
+    return true;
+}
+
+/*~*~*~*
+   hash delete - linear probe
+*~**/
+bool HashTable::remove(Student &itemOut) {
+    return false;
+}
+
+/*~*~*~*
+   hash search - linear probe
+   search for key
+   if found: 
+      - copy data to itemOut
+      - copy number of collisions for this key to noCol
+      - returns true
+   if not found, returns false
+*~**/
+bool HashTable::search(Student &itemOut, int &noCol, string key) {
+    int pos = _hash(key);
+    for (int collisions = 0; collisions < count; collisions++) {
+        if (!hashAry[pos].getOccupied()) return false;
+        if (hashAry[pos].getItem().getName() == key) {
+            itemOut = hashAry[pos].getItem();
+            noCol = hashAry[pos].getNoCollisions();
+            return true;
+        }
+        pos = (pos + 1) % hashSize;
+    }
+    return false;
+}

06-hash-tables/HashTable.h

@@ -0,0 +1,51 @@
+// Specification file for the Hash class
+
+#ifndef HASHTABLE_H_
+#define HASHTABLE_H_
+
+#include "HashNode.h"
+
+using std::string;
+
+class HashTable {
+private:
+    HashNode *hashAry;
+    int hashSize;
+    int count;
+
+public:
+    HashTable() {
+        count = 0;
+        hashSize = 53;
+        hashAry = new HashNode[hashSize];
+    }
+
+    HashTable(int n) {
+        count = 0;
+        hashSize = n;
+        hashAry = new HashNode[hashSize];
+    }
+
+    ~HashTable() { delete[] hashAry; }
+
+    int getCount() const { return count; }
+
+    int getSize() const { return hashSize; }
+
+    double getLoadFactor() const { return 100.0 * count / hashSize; }
+
+    bool isEmpty() const { return count == 0; }
+
+    bool isFull() const { return count == hashSize; }
+
+    bool insert(const Student &itemIn);
+
+    bool remove(Student &itemOut);
+
+    bool search(Student &itemOut, int &noCol, string key);
+
+private:
+    int _hash(string key) const;
+};
+
+#endif // HASHTABLE_H_

06-hash-tables/Student.h

@@ -0,0 +1,34 @@
+// Specification file for the Student class
+
+#ifndef STUDENT_H
+#define STUDENT_H
+
+using std::string;
+
+class Student {
+private:
+    double gpa;
+    string name;
+
+public:
+    Student() {
+        name = "";
+        gpa = -1;
+    }  // Constructor
+    Student(string n, double g) {
+        name = n;
+        gpa = g;
+    }  // Overloaded Constructor
+
+    // Setters and getters
+    void setName(string n) { name = n; }
+
+    void setGpa(double g) { gpa = g; }
+
+    string getName() const { return name; }
+
+    double getGpa() const { return gpa; }
+
+};
+
+#endif

06-hash-tables/main.cpp

@@ -0,0 +1,79 @@
+/*
+ CIS 22C
+ 
+ This program builds and searches a hash table.
+  
+ Written by: Iurii Tatishchev
+ Reviewed & Modified by: Iurii Tatishchev
+ IDE: CLion
+ 
+ */
+#include <iostream>
+#include <sstream>
+#include <cctype>
+
+#include "HashTable.h"
+
+using namespace std;
+
+void buildHash(HashTable &hash);
+
+void searchManager(HashTable &hash);
+
+int main() {
+    HashTable hash;
+    string option;
+
+    buildHash(hash);
+
+    cout << "Load Factor: " << hash.getLoadFactor() << endl;
+
+    searchManager(hash);
+
+    return 0;
+}
+
+/* **************************************************
+This function builds a hash table with data from the keyboard.
+It calls the insert() function that inserts the new data at the right location in the hash table.
+An input line contains the gpa of a student follow by name (assume it is a single word name)
+To stop reading enter "#"
+************************************************** */
+void buildHash(HashTable &hash) {
+    string line;
+    cout << "Enter gpa and name [# to stop reading]:" << endl;
+    getline(cin, line);
+    while (line != "#") {
+        stringstream temp(line); // create a stringstream named temp with data from line
+        double gpa;
+        string name;
+        temp >> gpa;  // read gpa from temp
+        temp >> name; // read name from temp
+        Student newStu(name, gpa);
+        hash.insert(newStu);
+        getline(cin, line);
+    }
+
+}
+
+/* **************************************************
+This function searches a hash table with user provided data.
+It calls the hash search function in a loop.
+To stop searching enter "#"
+************************************************** */
+void searchManager(HashTable &hash) {
+    string name;
+    cout << "Enter name [# to stop searching]:" << endl;
+    getline(cin, name);
+    while (name != "#") {
+        Student item;
+        int nc;
+        if (hash.search(item, nc, name)) {
+            cout << item.getName() << " " << item.getGpa() << " (" << nc << " collisions!)" << endl;
+        } else {
+            cout << name << " not found!" << endl;
+        }
+        getline(cin, name);
+    }
+
+}