queens

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <ctype.h>
#include <time.h>
#pragma warning(disable:4996)
typedef long long LL;
typedef unsigned long long ULL;
#define MAX(a,b) (((a)>(b))?(a):(b))
#define SETBIT(gpio,bit) ((gpio)|=(1u<<(bit)))
#define RESETBIT(gpio,bit) ((gpio)&=~(1u<<(bit)))
#define READBIT(gpio,bit) (((gpio)>>(bit))&1)
#define CROL(X,i,n) ((((X)<<(i))|((X)>>((n)-(i))))&((1ull<<(n))-1ull))
#define CROR(X,i,n) ((((X)>>(i))|((X)<<((n)-(i))))&((1ull<<(n))-1ull))
int queens[25] = { 0 }, rows = 0, ans = 0;
char check(int k, int p){//row k col p
    int i;
    for(i = 1; i < k; i++){
        if((queens[i] == p) || (abs(queens[i] - p) == abs(k - i))){
            return 0;
        }
    }
    return 1;
}
void dfs(int k){
    int i;
    if(k > rows){
        if(ans < 3){
            for(i = 1; i < k; i++){
                printf("%d ", queens[i]);
            }
            putchar('\n');
        }
        ans++; return;
    }
    else{
        for(i = 1; i <= rows; i++){
            if(check(k, i)){
                queens[k] = i;
                dfs(k + 1);
            }
            queens[k] = 0;
        }
    }
}
int main(){
#ifdef _DEBUG
    FILE *fp = freopen("../../../input.txt", "r", stdin);
    //FILE *fp2 = freopen("output.txt", "w", stdout);
#endif // _DEBUG
    scanf("%d", &rows);
    dfs(1);
    printf("%d\n", ans);
#ifdef _DEBUG
    freopen("CON", "r", stdin);
    //freopen("CON", "w", stdout);
    system("pause");
#endif // _DEBUG
    return 0;
}