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checkin #309

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1 change: 1 addition & 0 deletions .idea/.name
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33 changes: 33 additions & 0 deletions .idea/workspace.xml
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110 changes: 58 additions & 52 deletions src/com/interview/graph/BinaryMinHeap.java
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Original file line number Diff line number Diff line change
Expand Up @@ -7,23 +7,21 @@

/**
* Date 04/06/2013
*
* @author Tushar Roy
*
* Data structure to support following operations
* extracMin - O(logn)
* addToHeap - O(logn)
* containsKey - O(1)
* decreaseKey - O(logn)
* getKeyWeight - O(1)
* Data structure to support following operations extracMin - O(logn)
* addToHeap - O(logn) containsKey - O(1) decreaseKey - O(logn)
* getKeyWeight - O(1)
*
* It is a combination of binary heap and hash map
* It is a combination of binary heap and hash map
*
*/
public class BinaryMinHeap<T> {

private List<Node> allNodes = new ArrayList<>();
private Map<T,Integer> nodePosition = new HashMap<>();
private Map<T, Integer> nodePosition = new HashMap<>();

public class Node {
int weight;
T key;
Expand All @@ -32,14 +30,14 @@ public class Node {
/**
* Checks where the key exists in heap or not
*/
public boolean containsData(T key){
public boolean containsData(T key) {
return nodePosition.containsKey(key);
}

/**
* Add key and its weight to they heap
*/
public void add(int weight,T key) {
public void add(int weight, T key) {
Node node = new Node();
node.weight = weight;
node.key = key;
Expand All @@ -53,8 +51,8 @@ public void add(int weight,T key) {
Node parentNode = allNodes.get(parentIndex);
Node currentNode = allNodes.get(current);
if (parentNode.weight > currentNode.weight) {
swap(parentNode,currentNode);
updatePositionMap(parentNode.key,currentNode.key,parentIndex,current);
swap(parentNode, currentNode);
updatePositionMap(parentNode.key, currentNode.key, parentIndex, current);
current = parentIndex;
parentIndex = (parentIndex - 1) / 2;
} else {
Expand All @@ -66,31 +64,31 @@ public void add(int weight,T key) {
/**
* Get the heap min without extracting the key
*/
public T min(){
public T min() {
return allNodes.get(0).key;
}

/**
* Checks with heap is empty or not
*/
public boolean empty(){
public boolean empty() {
return allNodes.size() == 0;
}

/**
* Decreases the weight of given key to newWeight
*/
public void decrease(T data, int newWeight){
public void decrease(T data, int newWeight) {
Integer position = nodePosition.get(data);
allNodes.get(position).weight = newWeight;
int parent = (position -1 )/2;
while(parent >= 0){
if(allNodes.get(parent).weight > allNodes.get(position).weight){
int parent = (position - 1) / 2;
while (parent >= 0) {
if (allNodes.get(parent).weight > allNodes.get(position).weight) {
swap(allNodes.get(parent), allNodes.get(position));
updatePositionMap(allNodes.get(parent).key,allNodes.get(position).key,parent,position);
updatePositionMap(allNodes.get(parent).key, allNodes.get(position).key, parent, position);
position = parent;
parent = (parent-1)/2;
}else{
parent = (parent - 1) / 2;
} else {
break;
}
}
Expand All @@ -101,7 +99,7 @@ public void decrease(T data, int newWeight){
*/
public Integer getWeight(T key) {
Integer position = nodePosition.get(key);
if( position == null ) {
if (position == null) {
return null;
} else {
return allNodes.get(position).weight;
Expand All @@ -112,7 +110,7 @@ public Integer getWeight(T key) {
* Returns the min node of the heap
*/
public Node extractMinNode() {
int size = allNodes.size() -1;
int size = allNodes.size() - 1;
Node minNode = new Node();
minNode.key = allNodes.get(0).key;
minNode.weight = allNodes.get(0).weight;
Expand All @@ -127,73 +125,81 @@ public Node extractMinNode() {

int currentIndex = 0;
size--;
while(true){
int left = 2*currentIndex + 1;
int right = 2*currentIndex + 2;
if(left > size){
while (true) {
int left = 2 * currentIndex + 1;
int right = 2 * currentIndex + 2;
if (left > size) {
break;
}
if(right > size){
if (right > size) {
right = left;
}
int smallerIndex = allNodes.get(left).weight <= allNodes.get(right).weight ? left : right;
if(allNodes.get(currentIndex).weight > allNodes.get(smallerIndex).weight){
if (allNodes.get(currentIndex).weight > allNodes.get(smallerIndex).weight) {
swap(allNodes.get(currentIndex), allNodes.get(smallerIndex));
updatePositionMap(allNodes.get(currentIndex).key,allNodes.get(smallerIndex).key,currentIndex,smallerIndex);
updatePositionMap(allNodes.get(currentIndex).key, allNodes.get(smallerIndex).key, currentIndex,
smallerIndex);
currentIndex = smallerIndex;
}else{
} else {
break;
}
}
return minNode;
}

/**
* Extract min value key from the heap
*/
public T extractMin(){
public T extractMin() {
Node node = extractMinNode();
return node.key;
}

private void printPositionMap(){
private void printPositionMap() {
System.out.println(nodePosition);
}

private void swap(Node node1,Node node2){
private void swap(Node node1, Node node2) {
int weight = node1.weight;
T data = node1.key;

node1.key = node2.key;
node1.weight = node2.weight;

node2.key = data;
node2.weight = weight;
}

private void updatePositionMap(T data1, T data2, int pos1, int pos2){
private void updatePositionMap(T data1, T data2, int pos1, int pos2) {
nodePosition.remove(data1);
nodePosition.remove(data2);
nodePosition.put(data1, pos1);
nodePosition.put(data2, pos2);
}
public void printHeap(){
for(Node n : allNodes){

public void printHeap() {
for (Node n : allNodes) {
System.out.println(n.weight + " " + n.key);
}
}
public static void main(String args[]){

public static void main(String args[]) {
BinaryMinHeap<String> heap = new BinaryMinHeap<String>();
heap.add(3, "Tushar");
heap.add(4, "Ani");
heap.add(8, "Vijay");
heap.add(10, "Pramila");
heap.add(5, "Roy");
heap.add(6, "NTF");
heap.add(2,"AFR");
heap.decrease("Pramila", 1);
// heap.add(3, "Tushar");
// heap.add(4, "Ani");
// heap.add(8, "Vijay");
// heap.add(10, "Pramila");
// heap.add(5, "Roy");
// heap.add(6, "NTF");
// heap.add(2,"AFR");
// heap.decrease("Pramila", 1);
// heap.printHeap();
// heap.printPositionMap();
heap.add(5, "Amira");
heap.add(3, "Afsar");
heap.add(2, "Ayaha");
heap.add(1, "Abdul");
heap.add(4, "Afraz");
heap.printHeap();
heap.printPositionMap();
}
}