Dmitri Makovetskiy

public class BTree { public static void main(String[] args) { Btree2 tree=new Btree2(); tree.add(10); tree.add(20); tree.add(50); tree.add(100); tree.add(12); tree.add(1); tree.print(); tree.remove(50); } } class Btree2{ private Node head; public void add(int number){ // builds a binary tree Node node=new Node(number); if(head==null){ head=node; } Node current=head; while(true){ if(number<current.info){ if(current.left==null){ current.left=node; return; } else{ current=current.left; } } if(number>current.info){ if(current.right==null){ current.right=node; return; } else{ current=current.right; } } } } void print(){ print(head); } public void print(Node unit){ // prints the tree if(unit==null) return; print(unit.left); System.out.println(unit.info); print(unit.right); } public void remove(int number){// removes the head Node left = null; Node right = null; if(head.info==number){ left=head.left; right=head.right; } if(left==null && right==null){ head=null; } if(left!=null){ head=left; addUnit(right);// why do i need the addUnit? } else{ head=right; } remove(head,number); } private void remove(Node unit, int number) { // removes the corresponding nodes and misplacing them under the correct node. Node right = null; Node left = null; if(unit==null) return; remove(unit.left, number); // recursion, checking the left nodes. if(unit.left!=null) if(unit.left.info==number){ right=unit.left.left; // moving the nodes to the left side. unit.left=unit.left.right; addUnit(right); // why addUnit, right only and not left too? } if(unit.right!=null) if(unit.right.info==number){ left=unit.right.left; // moving the node chain to the right node. unit.right=unit.right.right; addUnit(left); // why addUnit , left only and not right node too?? } remove(unit.right, number); // recursion checking the right side. } private void addUnit(Node unit){ // builds a binary tree. Node current=head; if(unit==null) return; while (true) { if(unit.info<current.info){ if(current.left==null){ current.left=unit; return; } else current=current.left; } else{ if(current.right==null){ current.right=unit; return; } else current=current.right; } } } } class Node{ int info; Node right; Node left; Node(int info){ this.info=info; } }

did i do it right. first, make a function to check the head , whether to remove it, and then call for a function to remove nodes from the body, and transfer the chain underneath to another node..

one thing that i didnt understand is why do you need addUnit(right), addUnit(left) .. in the order described in the remove functions?

David Newton wrote:Please KeepItDown.

So, follow the code: I'm still not convinced you ever work out anything on paper--this is a *critically* important skill.

1) What does BTree.add(int) do?
2) What does the Node constructor do?
3) Question answered, correct?

That's all it takes: you only had to look at a few lines of code to determine the answer.

Newton , i scanned the whole thing. i know where the info comes from

but what value does the current.info has got?

David Newton wrote:...

Is this code that you wrote yourself?

NO, NEWTON, it is my teachers code. i understand that. but i dont understand the line which i marked

public class BTreeEx3 { public static void main(String[] args) { BTree tree=new BTree(); tree.add(5); tree.add(6); tree.add(1); tree.add(19); tree.add(3); tree.add(10); tree.add(2); tree.print(); } } class BTree{ private Node head; public void add(int info){ Node node=new Node(info); if(head==null){ head=node; return; } Node current=head; while (true) { if(info<current.info){// what number is current.info. whats happening there. what number does it represent? if (current.left==null) { current.left=node; return; } else current = current.left; } else { if(info>current.info){ if (current.right==null) { current.right=node; return; } else current = current.right; } } } } //toLinkedList() public void print(){ print(head); } private void print(Node node){ if(node==null) return; print(node.left); System.out.println(node.info); print(node.right); } class Node{ int info; public Node(int info) { super(); this.info = info; } Node left; Node right; } }

the algorithm above should give me a binary tree. i have one question. what current.info represent? what number?

David Newton wrote:You're a ways off from being able to provide those services--best to focus on basics for now.

we are not talking about now, we are talking about future.


how difficult is it to convert a webpage from pc to iphone?

John Todd wrote:Man, you should really decide by now.
https://coderanch.com/t/505960/iphone/Mobile/learning-program-iphone-worth-it

TOD, i thought to combine iphone with my webmaster course that i am taking. may be i could offer a service that combines iphone with webdesign.

i wondered if that thing is possible

David Newton wrote:You start on the Apple iOS developer site, possibly by picking up a book or two, learning Objective-C, and buying a Mac if you don't already have one.

Yes, it will confuse you learning both at the same time: if you were more advanced at Java/programming in general, I don't think it would be a major issue. But it's even *more* important when using C-like languages to pay very close attention to what you're doing. And if your OO fundamentals are weak, the combination of C and Smalltalk isn't likely to go over very well.

thank you for pointing this up.

i need to be patient :(

what if i learned iphone first and java then, a question, just for curiousity

and where do you start.


i learn java now. will it confuse me learning them simultaneously?

Campbell Ritchie wrote:Do you have Pawn objects and Bishop objects and Knight objects, etc?

i do have all that!!!

here is my array of pieces in the main:

The class that is called ChessInterface

ChessPiece[][]pieces =new ChessPiece[9][9];


pieces[2][1]=new Pawn("Bpn1"); pieces[2][2]=new Pawn("Bpn2"); pieces[2][3]=new Pawn("Bpn3"); pieces[2][4]=new Pawn("Bpn4"); pieces[2][5]=new Pawn("Bpn5"); pieces[2][6]=new Pawn("Bpn6"); pieces[2][7]=new Pawn("Bpn7"); pieces[2][8]=new Pawn("Bpn8"); pieces [1][1]=new Rook("BR1"); pieces [1][2]=new Knight("BN1"); pieces [1][3]=new Bishop("BB1"); pieces [1][4]=new King("BKing"); pieces [1][5]=new Queen("BQueen"); pieces [1][6]=new Bishop("BB2"); pieces [1][7]=new Knight("BN2"); pieces [1][8]=new Rook("BR2"); pieces[7][1]=new Pawn("Wpn1"); pieces[7][2]=new Pawn("Wpn2"); pieces[7][3]=new Pawn("Wpn3"); pieces[7][4]=new Pawn("Wpn4"); pieces[7][5]=new Pawn("Wpn5"); pieces[7][6]=new Pawn("Wpn6"); pieces[7][7]=new Pawn("Wpn7"); pieces[7][8]=new Pawn("Wpn8"); pieces [8][1]=new Rook("WR1"); pieces [8][2]=new Knight("WN1"); pieces [8][3]=new Bishop("WB1"); pieces [8][4]=new King("WKing"); pieces [8][5]=new Queen("WQueen"); pieces [8][6]=new Bishop("WB2"); pieces [8][7]=new Knight("WN2"); pieces [8][8]=new Rook("WR2");

ChessPiece is the name of my abstract class:


abstract class ChessPiece { abstract public boolean isMoveValid(ChessPiece[][] pieces,int columnStart, int rowStart, int columnEnd, int rowEnd); abstract public String print(); abstract public String FindPiece(String chessPiece); abstract public boolean piecesCollision(ChessPiece[][]pieces,int rowStart,int columnStart ,int columnEnd,int rowEnd); }

all the algorithm of hte chess piece collsion is inside the method in the rook (or bishop class, they are quite similar..but different enough)

class Rook extends ChessPiece{ public boolean piecesCollision(ChessPiece[][]pieces,int rowStart,int columnStart ,int columnEnd,int rowEnd) {

what intrigues me. how that pieces array behaves? may be it doesnt work cause of jumbing between classes and methods\| cause i have an if condition that counts or is aware of whether there is an object or condition

David Newton wrote:The code above will not compile--do you understand that? You need to post the exact code that doesn't work the way you expect, you need to state how you want your code to work, and so on.

my code does compile. i used it for 3 days, i feed it with different values.


try to see whats the problem when you copy it and paste it. may be you are missing a bracket

David Newton wrote:If the debugged bishop code works, what's the issue? The rook code?

You're confusing on several levels... And please, *please* format your code.

The debugg works. cause i put everything in a class. but in my original code i put the things in one method and call it from the main. that kind of order makes it fail..
it doesnt pay attention to the objects.. it counts every piece as a null

David Newton wrote:(And I can't tell if you have a cut-and-paste error in your code, or if it's what you really mean: perhaps posting an explanation of your algorithm would also be useful to the dwindling number of people that are still trying to help.)

The bishop and the rook algorithm is based on the same principle they both dont work on the same principle


here is bishops debugged code. works..

just feed new numbers and see for yourself. you could also add or remove the nulls from an array.


class LinkedListEx2{ public static void main(String[] args){ String[][]pieces =new String[9][9]; pieces[2][1]="Twenty One"; // pieces[2][2]="Twenty Two"; pieces[2][3]="Twenty Three"; pieces[2][4]="Twenty Four"; pieces[2][5]="Twenty Five"; pieces[2][6]="Twenty Six"; pieces[2][7]="Twenty Seven"; pieces[2][8]="Twenty Seven"; pieces [1][1]="Twenty Eight"; pieces [1][2]="Twenty Eight"; pieces [1][3]="Twenty Eight"; pieces [1][4]="Twenty Eight"; pieces [1][5]="Twenty Eight"; pieces [1][6]="Twenty Eight"; pieces [1][7]="Twenty Eight"; pieces [1][8]="Twenty Seven"; pieces[7][1]="Twenty Seven"; pieces[7][2]="Twenty Eight"; pieces[7][3]="Twenty Eight"; pieces[7][4]="Twenty Eight"; // pieces[7][5]="Twenty Eight"; pieces[7][6]=null; pieces[7][7]=null; pieces[7][8]=null; pieces [8][1]="Twenty Seven"; pieces [8][2]="Twenty Eight"; pieces [8][3]="Twenty Eight"; pieces [8][4]="Twenty Eight"; pieces [8][5]="Twenty Eight"; pieces [8][6]=null; pieces [8][7]=null; pieces [8][8]=null; int rowStart=1; int rowEnd=8; int columnStart=1; int columnEnd=8; int columnX=columnEnd-columnStart;// This is a very important part!!!!!!!!!!!!!!!!!!!!!!!!1 int rowY=rowEnd-rowStart; // This is a very important part!!!!!!!!!!!!!!!!!!!!! boolean BishopNorthEast=false; boolean BishopNorthWest=false; boolean BishopSouthWest=false; boolean BishopSouthEast=false; int a=0; ////////////////////BishopNorthWest////////////////////////////////// //1-- if(columnX<0 && rowY<0){ // based on the values from columnX, rowY, the if condition will be executed (if start is bigger than end, and vice versa) while(pieces[rowStart-1-a][columnStart-1-a]==null && (columnStart-1-a)!=columnEnd && (rowStart-1-a)!=rowEnd){ // this loop does 2 things. // 1) count the squares from start to finish. // 2) count how many nulls there are. // if both conditions are satisfied , then the value "a" will be counted once each time the loop is executed. a++; } a=a+1; if(rowY<0 ){ // This is self explanatory rowY=rowY*(-1); } if(columnX<0){ columnX=columnX*(-1); } if(a<rowY && a><columnX){ // this condition simply wants to see whether a==columnX or rowX (which should be equal as the bishop moves in diagonal). if a==rowY/columnX, then // it means that java counted all the squares from start to finish as nulls.. there were no objects BishopNorthWest=false; System.out.println("BishopNorthWest A is "+a+" and this is the square places disparity "+ rowY); System.out.println("BishopNorthWest A is "+a+" and this is the square places disparity "+ columnX); System.out.println("BishopNorthWest value is flase"); } else{ BishopNorthWest=true; System.out.println("BishopNorthWest A is "+a+" and this is the square places disparity "+ columnX); System.out.println("BishopNorthWest A is "+a+" and this is the square places disparity "+ rowY); System.out.println("BishopNorthWest value is true"); } rowY=rowY*(-1); // this simply returns the rowY columnX to the way they used to be (negative ) if i dont do that // procedure... the code will do things i dont want it to do. it is marginal in importance.. // not critical, thought necessary columnX=columnX*(-1); } /////////////////////////////// BishopSouthEast ///////////////////////////////////// //2++ if (rowY>0 && columnX>0){ // the whole algorithm is same, but the first condition dictates how the <>-+ signs will be!! while(pieces[rowStart+1+a][columnStart+1+a]==null && (columnStart+1+a)!=columnEnd && (rowStart+1+a)!=rowEnd){ a++; } a=a+1; System.out.println("BishopSouthEast This is a "+a); if(a<rowY && a><columnX){ BishopNorthEast=false; System.out.println("BishopSouthEast This is a "+a+" and this is the square places disparity "+ rowY); System.out.println("BishopSouthEast This is a "+a+" and this is the square places disparity "+ columnX); System.out.println("BishopSouthEast This is a This value is false"); } else{ BishopNorthEast=true; System.out.println("BishopSouthEast This is a "+a+" and this is the square places disparity "+ columnX); System.out.println("BishopSouthEast This is a "+a+" and this is the square places disparity "+ rowY); System.out.println("BishopSouthEast This is a This value is true"); } } /////////////////////// BishopSouthWest////////////////////////////////////// BishopNorthEast//////////////////////////// if(rowY>0 && columnX<0){ while(pieces[rowStart+1+a][columnStart-1-a]==null && (columnStart-1-a)!=columnEnd && (rowStart+1+a)!=rowEnd){ a++; } a=a+1; if(rowY<0){ rowY=rowY*(-1); } if(columnX<0){ columnX=columnX*(-1); } if(a<rowY && a><columnX){ BishopSouthWest=false; System.out.println("BishopSouthWest This is a "+a+" and this is the square places disparity "+ rowY); System.out.println("BishopSouthWest This is a "+a+" and this is the square places disparity "+ columnX); System.out.println("BishopSouthWest This is a This value is false"); } else{ BishopSouthWest=true; System.out.println("BishopSouthWest This is a "+a+" and this is the square places disparity "+ columnX); System.out.println("BishopSouthWest This is a "+a+" and this is the square places disparity "+ rowY); System.out.println("BishopSouthWest This is a This value is true"); } } ///////////////////////////BishopNorthEast ////////////////////////////////////////BishopSouthWest////////////////////////////// //4+- if (rowY><0 && columnX>0){ while(pieces[rowStart-1-a][columnStart+1+a]==null && (columnStart+1+a)!=columnEnd && (rowStart-1-a)!=rowEnd){ a++; } a=a+1; if(rowY<0){ rowY=rowY*(-1); } if(columnX<0){ columnX=columnX*(-1); } if(a<rowY && a><columnX ){ BishopNorthEast=false; System.out.println("BishopNorthEast This is a "+a+" and this is the square places disparity "+ rowY); System.out.println("BishopNorthEast This is a "+a+" and this is the square places disparity "+ columnX); System.out.println("BishopNorthEast This is a This value is false"); } else{ BishopNorthEast=true; System.out.println("BishopNorthEast This is a "+a+" and this is the square places disparity "+ columnX); System.out.println("BishopNorthEast This is a "+a+" and this is the square places disparity "+ rowY); System.out.println("BishopNorthEast This is a This value is true"); } } } } >

David Newton wrote:I think you misunderstood me: an "error" is anything that doesn't work the way you want it to. What I asked for was a board configuration that exhibits the error--rather than making us reverse engineer *everything*, provide an SSCCE for us to examine. It's difficult enough to read your code without having to also figure out how to create a scenario that causes the undesired behavior.

newton, i can give you the code after i debugged it. it has a different array (of strings) and 4 variables to change to move the pieces (rowstart, columnstart.....), other than that everything else is the same. all the algorithm
is copied and pasted....

class rook{ public static void main(String[] args){ String[][]pieces =new String[9][9]; pieces[2][1]="Twenty One"; // pieces[2][2]="Twenty Two"; pieces[2][3]="Twenty Three"; pieces[2][4]="Twenty Four"; pieces[2][5]="Twenty Five"; pieces[2][6]="Twenty Six"; pieces[2][7]="Twenty Seven"; pieces[2][8]="Twenty Seven"; pieces [1][1]="Twenty Eight"; pieces [1][2]="Twenty Eight"; pieces [1][3]="Twenty Eight"; pieces [1][4]="Twenty Eight"; pieces [1][5]="Twenty Eight"; pieces [1][6]="Twenty Eight"; pieces [1][7]="Twenty Eight"; pieces [1][8]="Twenty Seven"; pieces[7][1]="Twenty Seven"; pieces[7][2]="Twenty Eight"; pieces[7][3]="Twenty Eight"; pieces[7][4]="Twenty Eight"; // pieces[7][5]="Twenty Eight"; pieces[7][6]=null; pieces[7][7]="Twenty Seven"; //pieces[7][8]="Twenty Seven"; pieces [8][1]="Twenty Seven"; pieces [8][2]="Twenty Eight"; pieces [8][3]="Twenty Eight"; pieces [8][4]="Twenty Eight"; pieces [8][5]="Twenty Eight"; pieces [8][6]=null; //pieces [8][7]="Twenty Eight"; pieces [8][8]=null; int rowStart = 8; int rowEnd=7; int columnStart = 8; int columnEnd=8; boolean isRookMovingRight=false; boolean isRookMovingLeft=false; boolean isRookMovingDown=false; boolean isRookMovingUp=false; int b=0; int rowX=rowEnd-rowStart; int columnY=columnEnd-columnStart; System.out.println("rowX "+rowX); System.out.println("columnY "+columnY); //while(pieces[rowStart-1-a][columnStart+1+a]==null && (columnStart+1+a)!=columnEnd && (rowStart-1-a)!=rowEnd){ //////////////////////////////////////////////////////////////////////////////////////////////////////////// if(columnY>0 & rowX==0){ // RIGHT SIDE (CHECK FOR NULL) b=1; while(pieces[rowStart][columnStart+b+1]==null && columnStart+1+b!=columnEnd && pieces[rowEnd][columnEnd]==null){ b++; } System.out.println("B "+ b ); if(b!=columnY || columnY==0 || b==0 ){ isRookMovingRight=false; System.out.println("RIGHT SIDE "+"This is false "+ b+ " This is space "+ columnY); } else{ isRookMovingRight=true; System.out.println("RIGHT SIDE "+"This is true "+ b+ " This is space "+ columnY); } // IF B SMALLER THAN THE DIFFERENCE BETWEEN COLUMNSTART & COLUMNEND (SPACESY) , GIVE FALSE. OTHERWISE GIVE TRUE. } ////////////////////////////////////////////////////////////////////////////////////////////////////// if(columnY<0 & rowX==0){ // LEFT SIDE (CHECK FOR NULL) while(pieces[rowStart][columnStart-1-b]==null && columnStart-b-1!=columnEnd && pieces[rowEnd][columnEnd]==null){ b++; } b=b+1; columnY=columnY*(-1); if(b!=columnY || columnY==0 || b==0 ){ isRookMovingLeft=false; System.out.println("LEFT SIDE "+"This is false "+ b+ " This is space "+ columnY); } else{ isRookMovingLeft=true; System.out.println("LEFT SIDE "+"This is true "+ b+ " This is space "+ columnY); } } ////////////////////////////////////////////////////////////////////////////////////////////////////////// if(columnY==0 & rowX>0){ // DOWN SIDE (CHECK FOR NULL) b=1; while(pieces[rowStart+b][columnStart]==null && rowStart+b!=rowEnd && pieces[rowEnd][columnEnd]==null){ // CHECKS THE down ROW. b++; } if(b!=rowX || rowX==0 || b==0 ){ isRookMovingDown=false; System.out.println("DOWN SIDE "+"This is false "+ b+ " This is space "+ rowX); } else{ isRookMovingDown=true; System.out.println("DOWN SIDE "+"This is true "+ b+ " This is space "+ rowX); } } ///////////////////////////////////////////////////////////////////////////////////// if(columnY==0 & rowX<0){ // UP SIDE (CHECK FOR NULL) // (array[columnStart-b]!=0 && array[columnStart-b]!=array[columnEnd]&& array[columnEnd]!=0 ) while(pieces[rowStart-1-b][columnStart]==null & rowStart-b!=rowEnd && pieces[rowEnd][columnEnd]==null){ // CHECKS THE UPPER ROW. b++; } rowX=rowX*(-1); if(b!=rowX || rowX==0 || b==0){ isRookMovingUp=false; System.out.println("UP SIDE "+"This is false"+" B is "+ b + " rowX is "+rowX); } else{ isRookMovingUp=true; System.out.println("UP SIDE "+"This is true "+" B is "+ b+ " row X is "+rowX ); } } //return isRookMovingUp | isRookMovingDown | isRookMovingLeft | isRookMovingRight; } }

i think conceptually something happens that prevents my if test to be executed. i dont know how to reach teh sscce code

David Newton wrote:It'd be a lot easier to help if you posted a board configuration that exhibits the error/

it doesnt show any error. the bishop piece simple moves to any position i ask it too and the game continues.
so for example,

bishop from 1,1 to 8,8. it will be there. and it doesnt listen to the rule .. if(pieces[][]==null... it considers everything as null