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Copy pathMap.java
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125 lines (94 loc) · 2.71 KB
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package hashmaps;
import java.util.ArrayList;
public class Map<K, V> {
ArrayList<MapNode<K, V>> buckets;
int count;
int numBuckets;
public Map() {
buckets = new ArrayList<>();
numBuckets = 5;
for (int i = 0; i < numBuckets; i++) {
buckets.add(null);
}
}
private int getBucketIndex(K key) {
int hc = key.hashCode();
int index = hc % numBuckets;
return index;
}
public void insert(K key, V value) {
int bucketIndex = getBucketIndex(key);
MapNode<K, V> head = buckets.get(bucketIndex);
while (head != null) {
if (head.key.equals(key)) {
head.value = value;
return;
}
head = head.next;
}
head = buckets.get(bucketIndex);
MapNode<K, V> newnode = new MapNode<>(key, value);
newnode.next = head;
buckets.set(bucketIndex, newnode);
count++;
double loadfactor = (count * 1.0) / numBuckets;
if (loadfactor > 0.7) {
rehash();
}
}
public int size() {
return count;
}
public V getValue(K key) {
int bucketIndex = getBucketIndex(key);
MapNode<K, V> head = buckets.get(bucketIndex);
while (head != null) {
if (head.key.equals(key)) {
return head.value;
}
head = head.next;
}
return null;
}
public double loadfactor() {
double loadfactor = (count * 1.0) / numBuckets;
return loadfactor;
}
public V removeKey(K key) {
int bucketIndex = getBucketIndex(key);
MapNode<K, V> head = buckets.get(bucketIndex);
MapNode<K, V> prev = null;
while (head != null) {
if (head.key.equals(key)) {
if (prev != null) {
prev.next = head.next;
} else {
buckets.set(bucketIndex, head.next);
}
count--;
return head.value;
}
prev = head;
head = head.next;
}
return null;
}
private void rehash() {
ArrayList<MapNode<K, V>> temp = buckets;
buckets = new ArrayList<>();
for (int i = 0; i < 2 * numBuckets; i++) {
buckets.add(null);
}
count = 0;
numBuckets = numBuckets * 2;
for (int i = 0; i < temp.size(); i++) {
MapNode<K, V> head = temp.get(i);
while (head != null) {
K key = head.key;
V value = head.value;
insert(key, value);
head = head.next;
}
}
}
}