Problem Solving with code – Speeding Fine

We are going to start a series of posts on code problem solving. This will really help you guys that are self taught software developers. No matter how simple or complex we get with these problems it’s always good to take 10 to 20 mins and practice. All of these post will be using Java but feel free to post your solutions using whatever language you like. I would encourage you to take the extra time to write some unit tests so that you know if your code works or not.

Solve the problem on paper or a whiteboard using pseudocode first and post a picture of your solution in the comments below!

Here is an example of some really rough code on paper that I was writing to solve another problem.

The first problem we are going to talk about is speeding fine.

Below is the solution to the speeding fine problem. Post a link to an image of how you solved it or create your own gist for everyone to see.

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How to create a bubble sort with Java and Haxe

There are tones of posts online that cover bubble sort. Lately I’ve been brushing up on my Java and also I like Haxe so here are two videos covering bubble sort in each of the two languages.

Java Bubble Sort Algorithm

 

import java.util.Arrays;

/**
 * Created by matthew.wallace on 2/10/17.
 */
public class Main {

    public static void main(String[] args) {

        int[] list = {4,6,2,90,245,3,21,356,42};

        System.out.println("before sort : " + Arrays.toString(list));
        int i,j,temp;

        for (i = 0; i < list.length - 1 ; i++) {
            for (j = 0; j < list.length - 1 - i ; j++) {

                if( list[j] > list[j + 1]) {
                    temp = list[j];
                    list[j] = list[j + 1];
                    list[j + 1] = temp;
                }
            }
        }

        System.out.println("after sort : " + Arrays.toString(list));
    }
}

 

Haxe Bubble Sort Algorithm

 

package ;
class Main {

    public function new() {

        var list:Array<Int> = [7,5,1,2,45,37,42,183,3];

        var temp:Int;

        trace("unsorted list : "+ list);

        for(i in 0...list.length - 1) {
            for(j in 0...list.length - 1 - i) {

                if ( list[j] > list[j + 1]) {
                    temp = list[j];
                    list[j] = list[j + 1];
                    list[j + 1] = temp;
                }
            }
        }

        trace("sorted list : "+ list);

    }

    public static function main() {
        new Main();
    }
}

How do you create a queue from stack algorithm

This will be the first in a series of posts on some common algorithms you can use to solve various problem. I find it super helpful to do one or two of these per day just to keep things fresh in your mind. These are especially helpful to know during coding interviews.

Queue from Stack Java Example.

 

Queue from Stack Haxe Example.

So what is a “Stack”. Well, it’s a container of objects to put it simply. These objects are put in using the last-in first-out out method. To explain this in layman terms lets imagine you have a box and you put in a nickel, a dime, a penny and a quarter in that order. You come back to the box a few seconds later and reach in one at a time to pull out the money that you put in. The order that you can expect the money would be in reverse because when removing from a stack you must remove from the top down. So the first item to leave the box would be the quarter, then the penny, then the dime, then the nickel.

Here is an example of creating and adding items to a Stack in Java.

import java.util.Stack;

public class Queue {
        private Stack<Integer> newStack;
        
     public Queue() {
	oldStack = new Stack<Integer>();
	newStack = new Stack<Integer>();
     }

     public boolean enqueue(int element) {
	  boolean rvalue = true;
		
	  try {
              newStack.push(new Integer(element));
	  } catch (Exception error) {
	       rvalue  = false;
	       System.out.println("There was an error adding the item to the Queue : " + error.getMessage());;
	  }
		
	  return rvalue;
       } 

}

Here is an example in Haxe of a Stack using a typed Array.

package ;
class Queue {

    var newStack:Array<Int> = [];

    public function new() {
    }

    public function enqueue(element:Int):Bool {

        var rvalue:Bool = true;


        try {
            newStack.push(element);
        } catch (error:Error) {
            rvalue = false;
            trace("Something went wrong with added an element to the Queue: " + error);
        }

        return rvalue;
    }

}

Next we talk about the concept of a “Queue”. The Queue is a container that uses the first-in first-out principle. In our example above when explaining what a stack does, in order to implement the same example regarding a queue you would have a box and you would place a nickel, a dime, a penny and a quarter into the box in that order and then when removing them you would expect the money to come out of the box in the order in which you placed it, so you would see a nickel come out of the box first followed by the dime, then the penny, then lastly the quarter.

Here is an example of using some Queue logic with a Java Stack.

import java.util.Stack;

public class Queue {
	
	private Stack<Integer> oldStack;
	private Stack<Integer> newStack;
	private int topElement = -1;
	public Queue() {
		oldStack = new Stack<Integer>();
		newStack = new Stack<Integer>();
	}
	
	public Integer dequeue() {
		topElement = -1;
		if(oldStack.empty()) {
			while(!newStack.empty()) {
				topElement = newStack.peek();
				oldStack.push(topElement);
				newStack.pop();
			}
		}
		
		if(!oldStack.empty()) {
			Integer i = oldStack.peek();
			topElement = i.intValue();
			oldStack.pop();
		}
		
		return topElement;
	}
}

Here is an example of creating Queue logic with a Haxe typed Array.

package ;
import haxe.io.Error;
class Queue {

    var oldStack:Array<Int> = [];
    var newStack:Array<Int> = [];
    var topElement:Int = -1;

    public function new() {
    }

    public function dequeue():Int {

        topElement = -1;

        if(oldStack.length <= 0) {
            while(newStack.length > 0) {
                topElement = newStack.pop();
                oldStack.push(topElement);
            }
        }

        if(oldStack.length > 0) {
            topElement = oldStack.pop();
        }

        return topElement;
    }
}

 

Haxe Video Tutorials

Haxe Examples

If you have followed me for a while then you know that Haxe has always been something I’m interested  in, so I’ve started a new learning site. If you have not yet taken the time to see if it’s a cross-platform toolkit that you would like to use then you should check out the Haxe how to video tutorials that I’m creating over at the Haxe Examples website.

If you are a Haxe developer and you would like to contribute to the community then please hit me up on twitter. I’d like to have more of you contribute videos to the site as well. @matthewswallace

Checkout our first video on how to install Haxe and run your first Haxe program. 

Daily Haxe – October 5th 2016

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Domagoj Štrekelj

I’m working on Mokha (https://github.com/dstrekelj/mokha), which is a small 2D framework for Kha. It’s a pet project, not exactly ready for the public, but I hope others will find it useful in time. Just added a room-by-room camera follow style

Rafael Oliveira
I’m working in a 3d engine for Kha, there is no name yet (I’m not good at choosing lib names), but for now it’s just Sd3 (https://github.com/RafaelOliveira/Sd3). The objective is to create a simple engine that can run in mobile browsers. screenshot: http://1.1m.yt/GBwaglO.png Two demos: http://sudoestegames.com/play/3dtesthttp://sudoestegames.com/play/race in desktop the two demos uses a shader with lights, but if you open in a mobile browser, it will use a shader with no lights (for a better performance), and it will use the whole screen of the device. There is no touch controls yet.

YellowAfterlife
I wrote a GML->JS transpiler in Haxe which produces code compatible with what GameMaker itself outputs, therefore making it possible to make something similar to try.haxe but for GM and with client-side compilation.
http://yal.cc/r/gmlpen/


Matthew Wallace
Currently I’m creating the first of many courses on Haxe that I’ll be publishing to Udemy https://www.udemy.com/user/matthewwallace/

Daily Haxe

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Let’s show off what we are all up to in the Haxe community. Join the #dailyhaxe channel on Discord and I’ll pick the most interesting of what is going on and post it for you guys. It will be a great way to meet the community and start conversations about what people are working on or looking to do in the Haxe community.