Generate random chess position: Difference between revisions

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 No requirement is made regarding the probability distribution of your method, but your program should be able to span a reasonably representative sample of all possible positions.  For instance, programs that would always generate positions with say five pieces on the board, or with kings on a corner, would not be considered truly random.
+=={{header|C++}}==
+<lang cpp>
+#include <ctime>
+#include <iostream>
+#include <string>
+#include <algorithm>
+class chessBoard {
+public:
+    void generateRNDBoard( int brds ) {
+        int a, b, i; char c;
+        for( int cc = 0; cc < brds; cc++ ) {
+            memset( brd, 0, 64 );
+            std::string pieces = "PPPPPPPPNNBBRRQKppppppppnnbbrrqk";
+            random_shuffle( pieces.begin(), pieces.end() );
+            while( pieces.length() ) {
+                i = rand() % pieces.length(); c = pieces.at( i );
+                while( true ) {
+                    a = rand() % 8; b = rand() % 8;
+                    if( brd[a][b] == 0 ) {
+                        if( c == 'P' && !b || c == 'p' && b == 7 ||
+                          ( ( c == 'K' || c == 'k' ) && search( c == 'k' ? 'K' : 'k', a, b ) ) ) continue;
+                        break;
+                    }
+                }
+                brd[a][b] = c;
+                pieces = pieces.substr( 0, i ) + pieces.substr( i + 1 );
+            }
+            print();
+        }
+    }
+private:
+    bool search( char c, int a, int b ) {
+        for( int y = -1; y < 2; y++ ) {
+            for( int x = -1; x < 2; x++ ) {
+                if( !x && !y ) continue;
+                if( a + x > -1 && a + x < 8 && b + y >-1 && b + y < 8 ) {
+                    if( brd[a + x][b + y] == c ) return true;
+                }
+            }
+        }
+        return false;
+    }
+    void print() {
+        int e = 0;
+        for( int y = 0; y < 8; y++ ) {
+            for( int x = 0; x < 8; x++ ) {
+                if( brd[x][y] == 0 ) e++;
+                else {
+                    if( e > 0 ) { std::cout << e; e = 0; }
+                    std::cout << brd[x][y];
+                }
+            }
+            if( e > 0 ) { std::cout << e; e = 0; }
+            if( y < 7 ) std::cout << "/";
+        }
+        std::cout << " w - - 0 1\n\n";
+        for( int y = 0; y < 8; y++ ) {
+            for( int x = 0; x < 8; x++ ) {
+                if( brd[x][y] == 0 ) std::cout << ".";
+                else std::cout << brd[x][y];
+            }
+            std::cout << "\n";
+        }
+        std::cout << "\n\n";
+    }
+    char brd[8][8];
+};
+int main( int argc, char* argv[] ) {
+    srand( ( unsigned )time( 0 ) );
+    chessBoard c;
+    c.generateRNDBoard( 2 );
+    return 0;
+}
+</lang>
+{{out}}
+<pre>
+R6/2bnQP1K/br1N1BP1/nPkp1P2/2p1P1P1/4Ppqp/p1r1ppp1/1PNR3B w - - 0 1
+.R......
+..bnQP.K
+br.N.BP.
+nPkp.P..
+..p.P.P.
+....Ppqp
+p.r.ppp.
+.PNR...B
+n1k2bp/1PppQpb1/N1p4p/1B2P1K1/1RB2P2/pPR1Np2/P1r1rP1P/P2q3n w - - 0 1
+.n.k..bp
+.PppQpb.
+N.p....p
+.B..P.K.
+.RB..P..
+pPR.Np..
+P.r.rP.P
+P..q...n
+</pre>
 =={{header|J}}==