HackerRank : Week of Code 24 – Simplified Chess Engine

By | October 12, 2016

Chess is a very popular game played by hundreds of millions of people. Nowadays, we have chess engines such asStockfish and Komodo to help us analyze games. These engines are very powerful pieces of well-developed software that use intelligent ideas and algorithms to analyze positions and sequences of moves, as well as find tactical ideas. Consider the following simplified version of chess:

  • Board: It’s played on a board between two players named Black and White.
  • Pieces and Movement:
    • White initially has pieces and Black initially has pieces.
    • There are no Kings and no Pawns on the board. Each player has exactly one Queen, at most two Rooks, and at most two minor pieces (i.e., a Bishop and/or Knight).
    • Each piece’s possible moves are the same as in classical chess, and each move made by any player counts as a single move.
    • There is no draw when positions are repeated as there is in classical chess.
  • Objective: The goal of the game is to capture the opponent’s Queen without losing your own.

Given and the layout of pieces for games of simplified chess, implement a very basic (in comparison to the real ones) engine for our simplified version of chess with the ability to determine whether or not White can win in moves (regardless of how Black plays) if White always moves first. For each game, print YES on a new line if White can win under the specified conditions; otherwise, print NO.

Input Format

The first line contains a single integer, , denoting the number of simplified chess games. The subsequent lines define each game in the following format:

  • The first line contains three space-separated integers denoting the respective values of (the number of White pieces), (the number of Black pieces), and (the maximum number of moves we want to know if White can win in).
  • The subsequent lines describe each chesspiece in the format t c r, where is a character denoting the type of piece (where is Queen, is Knight, is Bishop, and is Rook), and and denote the respective column and row on the board where the figure is placed (where and ). These inputs are given as follows:
    • Each of the subsequent lines denotes the type and location of a White piece on the board.
    • Each of the subsequent lines denotes the type and location of a Black piece on the board.

Constraints

  • It is guaranteed that the locations of all pieces given as input are distinct.
  • Each player initially has exactly one Queen, at most two Rooks and at most two minor pieces.

Output Format

For each of the games of simplified chess, print whether or not White can win in moves on a new line. If it’s possible, print YES; otherwise, print NO.

Sample Input

1
2 1 1
N B 2
Q B 1
Q A 4

Sample Output

YES

Explanation

We play games of simplified chess, where the initial piece layout is as follows:

simplified-chess.png

White is the next to move, and they can win the game in move by taking their Knight to and capturing Black’s Queen. Because it took move to win and , we print YES on a new line.

Solution

Working on the Solution. In case you want any suggestions or the completed code, 
please comment on the post.


public static void main(String[] args) {

		Scanner scan= new Scanner(System.in);
		
		int g= scan.nextInt();
		int w=scan.nextInt();
		int b= scan.nextInt();
		int m= scan.nextInt();
		scan.nextLine();
		int blackQueenRow=0;
		int blackQueenColumn=0;
		
		
		Map <String, ArrayList> mapBlack=  new HashMap<String, ArrayList>();
		Map <String, ArrayList> mapWhite= new HashMap<String, ArrayList>();
		
		
		for(int i=0;i<w;i++)
		{
			ArrayList bList= new ArrayList(); 
			String pawn = scan.next(), c = scan.next(),  r = scan.next(); 
			pawn=pawn+i;
			
			int column=0;
			
			switch (c) {
			case "A":
				column=1;
				break;
			case "B":
				column=2;
				break;
			case "C":
				column=3;
				break;
			case "D":
				column=4;
				break;
			}
			

			board[Integer.parseInt(r)-1][column-1]=pawn;
			bList.add(column); bList.add(Integer.parseInt(r));			
			mapWhite.put(pawn,bList);
		}
	
		for(int j=0;j<b;j++)
		{
			ArrayList wList= new ArrayList();
			String pawn = scan.next(), c = scan.next(), r = scan.next(); 
			
			int column=0;
			
			switch (c) {
			case "A":
				column=1;
				break;
			case "B":
				column=2;
				break;
			case "C":
				column=3;
				break;
			case "D":
				column=4;
				break;
			}
			
			if(pawn.equals("Q"))
			{
				blackQueenRow=column-1;
				blackQueenColumn=Integer.parseInt(r)-1;
			}
			
			pawn=pawn+j;
			
			
			board[Integer.parseInt(r)-1][column-1]=pawn;
			wList.add(column); wList.add(Integer.parseInt(r));
			mapBlack.put(pawn,wList);
		}

	/*	
		
		System.out.println(mapBlack);
		System.out.println(mapWhite);
*/
		
		
/*		for(int i=0;i<4;i++)
		{
			for(int j=0;j0;mm--)
		{
			for (Entry<String, ArrayList> entry : mapWhite.entrySet()) 
			{
			String key=entry.getKey();
			ArrayList wList= entry.getValue();

			String pType= String.valueOf(key.charAt(0));
			isMate=(checkMate(pType, wList.get(0), wList.get(1), blackQueenRow, blackQueenColumn));
			if(isMate==true)
				break;
			}
		}
		
		if(isMate==true)
			System.out.println("YES");
		else
			System.out.println("NO");
		
		
	}