洛谷_P1219 [USACO1.5] 八皇后 Checker Challenge_python写法

P1219 USACO1.5 八皇后 Checker Challenge - 洛谷 | 计算机科学教育新生态 (luogu.com.cn)

n = int(input())

a = [0 for _ in range(1,2*n+100)]   #标记行
b = [0 for _ in range(1,2*n+100)]   #标记列
c = [0 for _ in range(1,2*n+100)]   #标记左下到右上的对角线
d = [0 for _ in range(1,2*n+100)]   #标记左上到右下的对角线
sum = 0
def printf():
    global sum

    if sum <=2:
        for i in range(1,n+1):
            print(a[i],end=' ')
        print('\n',end='')
    sum += 1
def dfs(i):

    for j in range(1,n+1):
        # if i+j<n+1 and abs(i-j)<n+1 :
        if b[j] == 0 and d[i-j+n] == 0 and c[i+j]==0:
            a[i] = j
            b[j] = 1
            c[i + j] = 1
            d[i-j+n] = 1
            dfs(i+1)
            b[j] = 0
            c[i + j] = 0
            d[i-j+n] = 0

            if i==n :
                printf()
                return

dfs(1)
print(sum)

不知道该怎么优化了，输入13，这个案例跑起来超时了。