arjunrao87

public String reverse( String s ){
  char[] c = s.toCharArray();
  int size = c.length;
  for( int i = 0; i<size/2; i ++ ){
    char temp = c[i];
    c[i] = c[size - i - 1];
    c[size - i - 1] = temp;;
  }
  return new String( c );
}

arjunrao87

public int recursiveFibonacci( int n ){
  if ( n<0 ){
    return -1;
  }
  if( n == 0 || n == 1 ){
    return 1;
  }
  return recursiveFibonacci( n -1 ) + recursiveFibonnaci( n - 2 );
}

arjunrao87

public boolean isPrime( int n ){
  if( n<0 )
    return false;
  if( n>0 && n <= 3  ){
    return true;
  }
  boolean isPrime = true;
  for( int i = 2; i< n/2; i++ ){
    if( n % i == 0 ){
      isPrime = false;

arjunrao87

//Method 1 : Time : O(n^3), Space : O(1)
public boolean findLongestPalindrome( String word ){
  String longestWord = "";
  for( int i  = 0; i < word.length(); i++ ){
    for( int j = 0; j<word.length(); j++ ){
      if( i<= j ){
        String currentWord = word.substring( i, j );
        if( isPalindrome( currentWord ) && currentWord.length() > longestWord.length() ){
          longestWord = currentWord;
        }

arjunrao87

class Vertex{
  private int id;
  private List<Edge> adjacencies;
  private boolean isVisited;
  
  public Vertex( int id ){
    this.id = id;
    this.adjacencies = new ArrayList<Edge>();
  }
  

arjunrao87

public class GraphBFS{
  public void doBFS( Vertex source ){
    Queue<Vertex> verticesToVisit = new LinkedList<Vertex>();
    verticesToVisit.enqueue( source );
    source.setVisited( true );
    while( !verticesToVisit.isEmpty() ){
      Vertex currentVertex = verticesToVisit.dequeue();
      for( Edge edge : currentVertex.getAdjacencies() ) {
        Vertex destinationVertex = edge.getDestinationVertex();
        if( !destinationVertex.isVisited() ) {

arjunrao87

public class PrimsAlgorithm{
  public void findPrimsMST( Graph graph ){
    
    //Step 1 : Initialize necessary arrays
    int[] weights      = new int[graph.getNumOfVertices()];
    boolean[] visited  = new boolean[graph.getNumOfVertices()];
    int[] predecessors = new int[graph.getNumOfVertices()];
    
    for( int i = 0; i<weights.length; i++ ){
      weights[i] = Integer.MAX_VALUE;

arjunrao87

public void findRange( Node node, int k1, int k2 ){
  if( node == null || (k1>k2) ){
    return;
  }
  int data = node.getData();
  if( data >= k1 && data <= k2 ){
    System.out.println(data);
  }
  if( k1 < data ){
    findRange( node.getLeft(), k1, k2 );

arjunrao87

public void doLevelOrder( Node root ){
  Queue<Node> nodes = new Queue<Node>();
  nodes.queue( root );
  
  while( !queue.isEmpty() ){
    Node currentNode = queue.dequeue();
    print( currentNode );
    if( currentNode.getLeft != null ){
      nodes.enqueue( currentNode.getLeft() );
    }

arjunrao87

public void doSpiralOrder( Node root ){
  Queue<Node> queue = new Queue<Node>();
  Stack<Node> stack = new Stack<Node>();
  stack.push( root );
  boolean readStack = true;
  
  while( (readStack && !stack.isEmpty()) || (!readStack && !queue.isEmpty()) ){
    Node currentNode = null;
    if( readStack ){
      currentNode = stack.pop();