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;
}




Go: package main

import (
    "fmt"
    "math/rand"
    "strconv"
    "strings"
    "time"
)

var grid [8][8]byte

func abs(i int) int {
    if i >= 0 {
        return i
    } else {
        return -i
    }
}

func createFen() string {
    placeKings()
    placePieces("PPPPPPPP", true)
    placePieces("pppppppp", true)
    placePieces("RNBQBNR", false)
    placePieces("rnbqbnr", false)
    return toFen()
}

func placeKings() {
    for {
        r1 := rand.Intn(8)
        c1 := rand.Intn(8)
        r2 := rand.Intn(8)
        c2 := rand.Intn(8)
        if r1 != r2 && abs(r1-r2) > 1 && abs(c1-c2) > 1 {
            grid[r1][c1] = 'K'
            grid[r2][c2] = 'k'
            return
        }
    }
}

func placePieces(pieces string, isPawn bool) {
    numToPlace := rand.Intn(len(pieces))
    for n := 0; n < numToPlace; n++ {
        var r, c int
        for {
            r = rand.Intn(8)
            c = rand.Intn(8)
            if grid[r][c] == '\000' && !(isPawn && (r == 7 || r == 0)) {
                break
            }
        }
        grid[r][c] = pieces[n]
    }
}

func toFen() string {
    var fen strings.Builder
    countEmpty := 0
    for r := 0; r < 8; r++ {
        for c := 0; c < 8; c++ {
            ch := grid[r][c]
            if ch == '\000' {
                ch = '.'
            }
            fmt.Printf("%2c ", ch)
            if ch == '.' {
                countEmpty++
            } else {
                if countEmpty > 0 {
                    fen.WriteString(strconv.Itoa(countEmpty))
                    countEmpty = 0
                }
                fen.WriteByte(ch)
            }
        }
        if countEmpty > 0 {
            fen.WriteString(strconv.Itoa(countEmpty))
            countEmpty = 0
        }
        fen.WriteString("/")
        fmt.Println()
    }
    fen.WriteString(" w - - 0 1")
    return fen.String()
}

func main() {
    rand.Seed(time.Now().UnixNano())
    fmt.Println(createFen())
}