Task: Generate random chess position

C: #include <stdio.h>
#include <math.h>
#include <string.h>
#include <stdlib.h>
#include <time.h>

#define TRUE 1
#define FALSE 0

typedef int bool;

char grid[8][8];

void placeKings() {
    int r1, r2, c1, c2;
    for (;;) {
        r1 = rand() % 8;
        c1 = rand() % 8;
        r2 = rand() % 8;
        c2 = rand() % 8;
        if (r1 != r2 && abs(r1 - r2) > 1 && abs(c1 - c2) > 1) {
            grid[r1][c1] = 'K';
            grid[r2][c2] = 'k';
            return;
        }
    }
}

void placePieces(const char *pieces, bool isPawn) {
    int n, r, c;
    int numToPlace = rand() % strlen(pieces);
    for (n = 0; n < numToPlace; ++n) {
        do {
            r = rand() % 8;
            c = rand() % 8;
        }
        while (grid[r][c] != 0 || (isPawn && (r == 7 || r == 0)));
        grid[r][c] = pieces[n];
    }
}

void toFen() {
    char fen[80], ch;
    int r, c, countEmpty = 0, index = 0;
    for (r = 0; r < 8; ++r) {
        for (c = 0; c < 8; ++c) {
            ch = grid[r][c];
            printf("%2c ", ch == 0 ? '.' : ch);
            if (ch == 0) {
                countEmpty++;
            }
            else {
                if (countEmpty > 0) {
                    fen[index++] = countEmpty + 48;
                    countEmpty = 0;               
                }
                fen[index++] = ch;
            }
        }
        if (countEmpty > 0) {
            fen[index++] = countEmpty + 48;
            countEmpty = 0;
        }
        fen[index++]= '/';
        printf("\n");
    }
    strcpy(fen + index, " w - - 0 1");
    printf("%s\n", fen);
}

char *createFen() {
    placeKings();
    placePieces("PPPPPPPP", TRUE);
    placePieces("pppppppp", TRUE);
    placePieces("RNBQBNR", FALSE);
    placePieces("rnbqbnr", FALSE);
    toFen();
}

int main() {
    srand(time(NULL));
    createFen();
    return 0;
}







Python: import random

board = [[" " for x in range(8)] for y in range(8)]
piece_list = ["R", "N", "B", "Q", "P"]


def place_kings(brd):
	while True:
		rank_white, file_white, rank_black, file_black = random.randint(0,7), random.randint(0,7), random.randint(0,7), random.randint(0,7)
		diff_list = [abs(rank_white - rank_black),  abs(file_white - file_black)]
		if sum(diff_list) > 2 or set(diff_list) == set([0, 2]):
			brd[rank_white][file_white], brd[rank_black][file_black] = "K", "k"
			break

def populate_board(brd, wp, bp):
	for x in range(2):
		if x == 0:
			piece_amount = wp
			pieces = piece_list
		else:
			piece_amount = bp
			pieces = [s.lower() for s in piece_list]
		while piece_amount != 0:
			piece_rank, piece_file = random.randint(0, 7), random.randint(0, 7)
			piece = random.choice(pieces)
			if brd[piece_rank][piece_file] == " " and pawn_on_promotion_square(piece, piece_rank) == False:
				brd[piece_rank][piece_file] = piece
				piece_amount -= 1

def fen_from_board(brd):
	fen = ""
	for x in brd:
		n = 0
		for y in x:
			if y == " ":
				n += 1
			else:
				if n != 0:
					fen += str(n)
				fen += y
				n = 0
		if n != 0:
			fen += str(n)
		fen += "/" if fen.count("/") < 7 else ""
	fen += " w - - 0 1\n"
	return fen

def pawn_on_promotion_square(pc, pr):
	if pc == "P" and pr == 0:
		return True
	elif pc == "p" and pr == 7:
		return True
	return False


def start():
	piece_amount_white, piece_amount_black = random.randint(0, 15), random.randint(0, 15)
	place_kings(board)
	populate_board(board, piece_amount_white, piece_amount_black)
	print(fen_from_board(board))
	for x in board:
		print(x)


start()