ndame.c

#include <stdio.h>
#include <stdlib.h>

int N;
int damen[100];

int columns[200], diag1[200], diag2[200];
#define DIAG1(row, column) (row)+(column)
#define DIAG2(row, column) (row)-(column)+N

int ndame(int row) {
    if (row == N)
        return 1;
    for (int i = 0; i < N; i++) {
        if (columns[i] || diag1[DIAG1(row, i)] || diag2[DIAG2(row, i)])
            continue;
        damen[row] = i;
        columns[i] = 1;
        diag1[DIAG1(row, i)] = 1;
        diag2[DIAG2(row, i)] = 1;
        if (ndame(row+1))
            return 1;
        damen[row] = -1;
        columns[i] = 0;
        diag1[DIAG1(row, i)] = 0;
        diag2[DIAG2(row, i)] = 0;
    }
    return 0;
}

int main(int argc, char** argv) {
    if (argc < 2) {
        printf("Usage: %s N\n", argv[0]);
        return 1;
    }
    N = atoi(argv[1]);

    for(int c = 0; c < 200; c++)
        columns[c] = diag1[c] = diag2[c] = 0;
    ndame(0);
    for (int row = 0; row < N; row++) {
        for (int col = 0; col < N; col++)
            printf("%c", damen[row] == col ? '#' : '-');
        printf("\n");
    }
}