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#include <cstddef>
#include <iostream>
using namespace std;
template <class K, class V>
struct Node {
K key;
V value;
Node<K,V> *next;
};
template <class K, class V>
struct Map {
Node<K,V> **table;
int size;
};
template <class K, class V>
void initialize(Map<K,V> &map, int size)
{
map.table = new Node<K,V> *[size]; //Create a dynamic array of input size.
map.size = size; //Store the size in the struct Map.
for(int i = 0; i < size; i++) //Set everything in the array to NULL.
map.table[i] = NULL;
}
template <class K, class V>
void destroy(Map<K,V> &map)
{
int index = 0;
Node<K,V> *scout = map.table[index];
while( index != map.size)
{
if((scout == NULL) && (index != (map.size-1))) {
index++;
delete scout;
scout = map.table[index];
}
else if((scout == NULL) & (index == (map.size-1))) {
delete scout;
index++;
}
else {
Node<K,V> *destroyer = scout -> next; //Points destroyer at next node
delete scout; //Deletes the node that Q.head is pointing at.
scout = destroyer; //Points Q.head at the node destroyer is pointing at.
if(destroyer == NULL) {
index++;
scout = map.table[index];
}
}
}
delete [] map.table;
map.table = NULL;
map.size = 0;
}
template <class K, class V>
void assign(Map<K,V> &map, K id, V contents)
{
Node<K,V> *item = new Node<K,V>; //Create a new node to enter values into.
//Fill the node with specified contents...
item -> key = id;
item -> value = contents;
item -> next = NULL;
int index = id % map.size; //Get the hash for the new key so we know what index to put it in.
if(map.table[index] == NULL) {//If the index on the array has no nodes in it...
map.table[index] = item;
return;
}
if(has_key(map, id) == true) {
Node<K,V> *scout = map.table[index]; //Create a searching node.
while( true ) {
if(scout -> key == id) {
scout -> value = contents;
break;
}
scout = scout -> next;
}
delete item; //Get rid of the node we created since we are just overwriting a previous one.
}
else {
//If the index already has a value in it, we must add the created node to a linked list on that index...
Node<K,V> *walker = map.table[index]; //Set a walker node to the first node in the table at the index.
while( true ) { //Walk through the indexed linked list.
if(walker -> next == NULL) //This will tell us if we've reached the end or not.
break;
walker = walker -> next; //Walk through the nodes at that particular index.
}
walker -> next = item; //When we find the end with the while loop above, walker will be at the last node on the list
//so we set the next value of walker, which should be NULL, to the newly created item.
}
}
template <class K, class V>
void remove(Map<K,V> &map, K id)
{
int index = id % map.size; //Get the index the key is at.
Node<K,V> *scout = map.table[index]; //Create a searching node.
Node<K,V> *previous = scout; //Create a tracker node so we know what node is behind us...(refer to following while loop)
while( true ) {
if(map.table[index] -> key == id) { //If the key is the first node at the index.
map.table[index] = map.table[index] -> next; //Sets the new first node to the next node.
delete scout;
break;
}
if(scout -> key == id) {
previous -> next = scout -> next; //This will point around the node we want to remove.
delete scout;
break;
}
scout = scout -> next; //Make scout take a step to next node.
}
}
template <class K, class V>
bool has_key(Map<K,V> map, K id) //**********This function is NOT working properly.
{
int column = id % map.size; //Find the index value that the key would be stored at, if it exists.
Node<K,V> *scout = map.table[column];
if(map.table[column] == NULL) //If the column has nothing in it...
return false;
while( true ) {
if(scout -> key == id)
return true;
if(scout -> next == NULL)
break;
scout = scout -> next;
}
return false;
}
template <class K, class V>
V lookup(Map<K,V> map, K id) //**************This function is working properly.
{
int index = id % map.size; //Find the index that the key is at.
Node<K,V> *scout = map.table[index]; //Create a searching node.
while( true ) {
if(scout -> key == id)
break;
if(scout -> next == NULL)
break;
scout = scout -> next;
}
return scout -> value;
}
// Overloaded hash functions, for different key types
int hash(int key, int size) {
return key % size;
}
int hash(char key, int size) {
return key % size;
}
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