codevita KNight move solution

Problem : Knight Moves

A Chess board position is accurately captured by Forsyth-Edwards notation and is abbreviated as FEN. A FEN "record" defines a particular game position, all in one text line and using only the ASCII character set. A FEN record contains six fields. A complete description of the FEN format to represent Chess positions can be found at here

For the purpose of this problem only consider first of the six fields of FEN. Before we describe the problem, let us look at how FEN maps to a board position. The following 5 images show board positions and its corresponding FEN representation. 

                    Figure 1.

This board position depicts initial position before any side has made a move. In FEN format this board position is represented as rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w

Let's say, White plays e4. Then the board position looks like shown below 

                    Figure 2.

This board position depicts the Chess board after White has played e4. In FEN format this board position is represented as rnbqkbnr/pppppppp/8/8/4P3/8/PPPP1PPP/RNBQKBNR b

Similarly, 3 more half-moves are depicted in following diagrams 

                          Figure 3.                                                  Figure 4.                                                     Figure 5. 


The FENs corresponding to Figure 3, 4 and 5 are represented as 

           3. rnbqkbnr/pppp1ppp/8/4P3/4P3/8/PPPP1PPP/RNBQKBNR w
           4. rnbqkbnr/pppp1ppp/8/4p3/4PP2/8/PPPP2PP/RNBQKBNR b
           5. rnbqkbnr/pppp1ppp/8/8/4Pp2/8/PPPP2PP/RNBQKBNR w 

Wikipedia describes first field of FEN format as follows 

Each rank is described, starting with rank 8 and ending with rank 1; within each rank, the contents of each square are described from file "a" through file "h". Following the Standard Algebraic Notation(SAN), each piece is identified by a single letter taken from the standard English names (pawn = "P", knight = "N", bishop = "B", rook = "R", queen = "Q" and king = "K").[1] White pieces are designated using upper-case letters ("PNBRQK") while black pieces use lowercase ("pnbrqk"). Empty squares are noted using digits 1 through 8 (the number of empty squares), and "/" separates ranks. 

The second field denotes whose move it is now. "w" depicts that it is White's turn to play and "b" indicates that it is Black's turn to play 

CodeVita Problem Statement 

Given a board position in FEN format, your task is to find out all the move(s) that Knight(s) of the playing side can make. 

Input Format: 

1. First line contains single FEN record, which corresponds to a particular board position and also indicates whose turn it is.

Output Format: 

1. The output must be printed as follows
   1. All legal moves that Knight can make must be in the format "[<Move Format>]"
   2. Where <Move Format> is move represented in format "[fromSquare][toSquare]"
2. See Example section for better understanding of output format
3. Follow Output printing specification to print the output in required format

Sample Input and Output

SNO.	INPUT	BOARD DEPICTION	OUTPUT
1	3k4/8/8/8/8/1K4R1/5R2/7N w		[]
2	3k4/8/8/8/8/6b1/5r2/K6N w		[h1g3, h1f2]
3	2k1b3/6n1/n7/5R2/8/8/8/4K3 b		[g7e6, g7f5, g7h5, a6b8, a6c7, a6c5, a6b4]

Print Specification: 

1. Should start with "[" and end with "]"
2. If more than one move is possible, moves should be separated by a comma followed by whitespace
3. Moves of a single bishop should be printed in Move Format. Scan the board from 8^th rank to 1^strank from a-file to h-file. Whichever square gets hit first, that move should be printed first.
4. If more than one bishop exists for side to move, then start scanning for bishop from 8^th rank to 1^st rank, left to right i.e. from a-file to h-file. Whichever bishop appears first, print all moves for that bishop first.
5. Verify your understanding of how printing should happen against examples shown above 

 SOLUTION

Please read notes

Thanks for visting.I'll soon update explition video
You can get board to string at -here don't forget to add w/b for turn

for download of source code mega link

       

            
/******************************************************KINGHT MOVE SOLUTION************************************************/
/*
Notes:-
1. it check KINGHT MOVE only
2. it not check correctness of fen inputr it assume that input string is correct (worng string also give worng ouput)
3. it not care about kings in board it also work if one knight pressent in board which is worng according to chess rules 
*/
#include<iostream>
using namespace std;//you can't use namespace in codevita so you can replace cout with std::cout as similler to cin


bool move_index_checker(int,int);
bool move_checker(int,int);
void moves(int,int);


string ip;//for fen input
char Board[9][9]=    // for storing chess board in matrix it. it store it in 1 to 8 index o index is empty
{{' ',' ',' ',' ',' ',' ',' ',' ',' '},
 {' ',' ',' ',' ',' ',' ',' ',' ',' '},
 {' ',' ',' ',' ',' ',' ',' ',' ',' '},
 {' ',' ',' ',' ',' ',' ',' ',' ',' '},
 {' ',' ',' ',' ',' ',' ',' ',' ',' '},
 {' ',' ',' ',' ',' ',' ',' ',' ',' '},
 {' ',' ',' ',' ',' ',' ',' ',' ',' '},
 {' ',' ',' ',' ',' ',' ',' ',' ',' '},
 {' ',' ',' ',' ',' ',' ',' ',' ',' '}},ch;//ch for storing turn of player
int count=1,i=1,j=1;
unsigned int a=0;


int main()
{
cout<<"Enter string=\n";
getline(cin,ip);//ip store the fen string
cout<<ip;
while(count<=64)// 
{
//cout<<"ip["<<a<<"]="<<ip[a];
if(ip[a]=='r'||ip[a]=='n'||ip[a]=='b'||ip[a]=='q'||ip[a]=='k'||ip[a]=='p'||ip[a]=='R'||ip[a]=='N'||ip[a]=='B'||ip[a]=='Q'||ip[a]=='K'||ip[a]=='P')
{
Board[i][j]=ip[a];
j++; count++;
}
else if(ip[a]=='/')
{
i++; j=1;
}
else
{
j+=(int)ip[a]-48;
//cout<<(int)ip[a]-48<<endl;
count+=(int)ip[a]-48;
}
a++;
}
(ip[a+1]=='w')? ch='N':ch='n';
cout<<ch<<endl<<endl;

int x[3]={1,0,0},y[3]={0,0,0};
for(i=1;i<9;i++)
{
for(j=1;j<9;j++)
{
if(Board[i][j]==ch)
{
x[x[0]]=i;y[x[0]]=j;
x[0]+=1;
}
}
}
cout<<'[';
if(x[1]!=0&&y[1]!=0)
{
moves(x[1],y[1]);
}
if(x[2]!=0&&y[2]!=0)
{
moves(x[2],y[2]);
}
cout <<']';
cout<<endl<<endl;
}


bool move_index_checker(int v,int h)
{
if((v>0&&v<9)&&(h>0&&h<9))
return true;
return false;
}

bool move_checker(int v,int h)
{
if(ch=='N')
{
if(Board[v][h]=='R'||Board[v][h]=='N'||Board[v][h]=='B'||Board[v][h]=='Q'||Board[v][h]=='K'||Board[v][h]=='P')
return false;
}
else
{
if(Board[v][h]=='r'||Board[v][h]=='n'||Board[v][h]=='b'||Board[v][h]=='q'||Board[v][h]=='k'||Board[v][h]=='p')
return false;
}
return true;
}

void moves(int v,int h)
{
if(move_index_checker(v-2,h+1)&&move_checker(v-2,h+1))
{
cout<<static_cast<char>(h+96)<<9-v<<static_cast<char>(h+96+1)<<9-(v-2)<<',';
}
if(move_index_checker(v-2,h-1)&&move_checker(v-2,h-1))
{
cout<<static_cast<char>(h+96)<<9-v<<static_cast<char>(h+96-1)<<9-(v-2)<<',';
}
if(move_index_checker(v+2,h+1)&&move_checker(v+2,h+1))
{
cout<<static_cast<char>(h+96)<<9-v<<static_cast<char>(h+96+1)<<9-(v+2)<<',';
}
if(move_index_checker(v+2,h-1)&&move_checker(v+2,h-1))
{
cout<<static_cast<char>(h+96)<<9-v<<static_cast<char>(h+96-1)<<9-(v+2)<<',';
}
if(move_index_checker(v-1,h+2)&&move_checker(v-1,h+2))
{
cout<<static_cast<char>(h+96)<<9-v<<static_cast<char>(h+96+2)<<9-(v-1)<<',';
}
if(move_index_checker(v-1,h-2)&&move_checker(v-1,h-2))
{
cout<<static_cast<char>(h+96)<<9-v<<static_cast<char>(h+96-2)<<9-(v-1)<<',';
}
if(move_index_checker(v+1,h+2)&&move_checker(v+1,h+2))
{
cout<<static_cast<char>(h+96)<<9-v<<static_cast<char>(h+96+2)<<9-(v+1)<<',';
}
if(move_index_checker(v+1,h-2)&&move_checker(v+1,h-2))
{
cout<<static_cast<char>(h+96)<<9-v<<static_cast<char>(h+96-2)<<9-(v+1)<<',';
}
}

       
 PartyLesh

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