KodeSeeker

/**

Good morning! Here's your coding interview problem for today.

This problem was asked by Yahoo.

Recall that a full binary tree is one in which each node is either a leaf node, or has two children. Given a binary tree, convert it to a full one by removing nodes with only one child.

For example, given the following tree:

KodeSeeker

import java.util.Arrays;

/**
*	quickselect is a selection algorithm to find the kth smallest element in an 
*	unordered list. Like quicksort, it is efficient in practice and has good 
*	average-case performance, but has poor worst-case performance. Quickselect 
*	and variants is the selection algorithm most often used in efficient 
*	real-world implementations.
*	
*	Quickselect uses the same overall approach as quicksort, choosing one 

KodeSeeker

import java.util.Arrays;

/**
 * Given an array of n integers nums and a target, find the number of index triplets i, j, k with 0 <= i < j < k < n
 * that satisfy the condition nums[i] + nums[j] + nums[k] < target.
 * <p>
 * For example, given nums = [-2, 0, 1, 3], and target = 2.
 * Return 2. Because there are two triplets which sums are less than 2:
 * <p>
 * [-2, 0, 1]

KodeSeeker

/**
Design and implement a TwoSum class. It should support the following operations: add and find.

add - Add the number to an internal data structure. find - Find if there exists any pair of numbers which sum is equal to the value.

For example,
add(1); add(3); add(5);
find(4) -> true
find(7) -> false
**/

KodeSeeker

/* package whatever; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
	public static void main (String[] args) throws java.lang.Exception

KodeSeeker

 public List<Integer> spiralOrder(List<ArrayList<Integer>> a){
 	
 	if( a == null || a.isEmpty()) {
 		return null;
 	}
 	// base case 3x3 then tweak 
 	int startRow = 0; 
 	int startCol = 0; 
 	
 	int endRow= a.size();

KodeSeeker

Studying for a Tech Interview Sucks, so Here's a Cheat Sheet to Help

This list is meant to be a both a quick guide and reference for further research into these topics. It's basically a summary of that comp sci course you never took or forgot about, so there's no way it can cover everything in depth. It also will be available as a gist on Github for everyone to edit and add to.

Data Structure Basics

###Array ####Definition:

• Stores data elements based on an sequential, most commonly 0 based, index.
• Based on tuples from set theory.

KodeSeeker

public static void main (String... args){
        
        UUID uid = UUIDs.timeBased();
        long time = getTimeFromUUID(uid);
        Date date = new Date(time);
        System.out.println(date);   
}
    
    static final long NUM_100NS_INTERVALS_SINCE_UUID_EPOCH = 0x01b21dd213814000L;
    public static long getTimeFromUUID(UUID uuid) {

KodeSeeker

public class Singleton
{
  private Singleton singleton;
  
  //make the constructor protected- to defeat instantiation.
  protected Singleton(){}
  
  public static Singleton getInstance() {
      if(singleton == null) {

KodeSeeker

/**
 * Convert from Postfix to Infix Notation 
 * Infix to Postfix :https://gist.github.com/KodeSeeker/f776c5477c3be3f43a77
 * Algo: 
 * 1) Walk through postfix expression
 * 2) If input is a num then  push to stack.
 * 3) If the input is a operator then pop the last two operatonds from stack and perform operation. Push result back onto stack.
 * 
 * Error condition : if you see a operator and there arent 2 operands in the left in the stack.
 *