3 different way Tree Traversal

=========================================================================
Node class for tree

class Node{
    int data;
    Node left;
    Node right;
}

=========================================================================
Case 1: pre-order 

Recursive

public static void preOrderRecursive(Node root){
    if(root == null)
        return;
		
    System.out.print(root.data + " ");		
    preOrderRecursive(root.left);
    preOrderRecursive(root.right);
}

NON-Recursive

public static void preOrderIterative(Node root){
    if(root == null)
        return;
		
    Stack<Node> unvisited = new Stack<Node>();
    unvisited.push(root);
	
    while(!unvisited.isEmpty()){
        Node node = unvisited.pop();
			
        System.out.print(node.data + " ");
        if(node.right != null)
            unvisited.push(node.right);
        if(node.left != null)
            unvisited.push(node.left);
    }	
}

=========================================================================
Case 2: in-order 

Recursive

public static void inOrderRecursive(Node root){
    if(root == null)
        return;	
	
    inOrderRecursive(root.left);
    System.out.print(root.data + " ");
    inOrderRecursive(root.right);
}

NON-Recursive

public static void inOrderIterative(Node root){
    if(root == null)
        return;
		
    Stack<Node> unvisited = new Stack<Node>();
		
    while(!unvisited.isEmpty() || root != null){
        if(root != null){
            unvisited.push(root);
            root = root.left;
        }else{
            root = unvisited.pop();
            System.out.print(root.data + " ");
            root = root.right;
        }
    }
}

========================================================================= 
Case 3: post-order 

Recursive

public static void postOrderRecursive(Node root){
    if(root == null)
        return;
		
    postOrderRecursive(root.left);
    postOrderRecursive(root.right);
    System.out.print(root.data + " ");		
}

NON-Recursive

public static void postOrderIterative(Node root){
    if(root == null)
        return;
		
    Stack<Node> finalStack = new Stack<Node>();
    Stack<Node> tempStack = new Stack<Node>();
	
    tempStack.push(root);
    while(!tempStack.isEmpty()){
        Node node = tempStack.pop();
        finalStack.push(node);
        if(node.left != null)
            tempStack.push(node.left);
				
        if(node.right != null)
            tempStack.push(node.right);
    }
	
    while(!finalStack.isEmpty()){
        Node node = finalStack.pop();
        System.out.print(node.data + " ");	
    }
}

Find a missing integer in an array of number

Find a missing integer in an array of number

Case 1: Sorted
Use two pointers to store previous and current value, and difference between two number should equal to 1.

public static int findMissing_Sorted(int[] input){
    if(input.length == 0)
        return 0;

    int prev = input[0];
    for(int i = 1 ; i < input.length ; i++){
        int curr = input[i];
        if((curr - prev) != 1)
            return (prev + 1);
        else
            prev = curr;
    }
    return 0;
}

Case 2: Unsorted
Get the sum of 1 to N, use formula sum = (N+1)*(N)/2
Minus the element in the array, and the remaining value is the missing number.

public static int findMissing_Unsorted(int[] input){
    if(input.length == 0)
        return 0;
   
    int N = 10;
    int max = (N + 1) * N / 2;
  
    for(int i = 0 ; i < input.length ; i++)
        max -= input[i];
   
    return max;
}

How to use *args and **kwargs in Python

from
http://www.saltycrane.com/blog/2008/01/how-to-use-args-and-kwargs-in-python/

http://docs.python.org/tutorial/controlflow.html#keyword-arguments

def test_var_args(farg, *args):
    print "formal arg:",farg
    for arg in args:
        print  "another arg:",arg
  


def test_var_kwargs(farg, **kwargs):
    print "formal arg:",farg
    for key in kwargs:
        print "another keyword arg: %s: %s" % (key, kwargs[key])

test_var_args(1, "two", 3, "four")
print '-'*40
test_var_kwargs(farg = 1, myarg2 = "two", myarg3 = 3, myarg4 = "four")

def test_var_args_call(arg1, arg2, arg3):
    print "arg1:", arg1
    print "arg2:", arg2
    print "arg3:", arg3

args = ("two", 3)
test_var_args_call(1, *args)

def test_var_args_call(arg1, arg2, arg3):
    print "arg1:", arg1
    print "arg2:", arg2
    print "arg3:", arg3

kwargs = {"arg3": 3, "arg2": "two"}
test_var_args_call(1, **kwargs)