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2*n皇后问题

#define _CRT_SECURE_NO_WARNINGS#include 
   
    const int maxn = 10;int n, ans, mp[maxn][maxn];int col_black[maxn], diag1_black[2 * maxn], diag2_black[2 * maxn];int col_white[maxn], diag1_white[2 * maxn], diag2_white[2 * maxn];void dfs(int k) {	if (n + 1 == k) {		ans++;		return;	}	for (int black = 1; black <= n; black++) {		for (int white = 1; white <= n; white++) {			if (col_black[black] || col_white[white])	continue;			if (black == white || !mp[k][black] || !mp[k][white])	continue;			if (diag1_black[k + black - 1] || diag2_black[k - black + n])	continue;			if (diag1_white[k + white - 1] || diag2_white[k - white + n])	continue;			col_black[black] = diag1_black[k + black - 1] = diag2_black[k - black + n] = 1; mp[k][black] = 0;			col_white[white] = diag1_white[k + white - 1] = diag2_white[k - white + n] = 1; mp[k][white] = 0;			dfs(k + 1);			col_black[black] = diag1_black[k + black - 1] = diag2_black[k - black + n] = 0; mp[k][black] = 1;			col_white[white] = diag1_white[k + white - 1] = diag2_white[k - white + n] = 0; mp[k][white] = 1;		}	}}int main() {	scanf("%d", &n);	for (int i = 1; i <= n; i++)		for (int j = 1; j <= n; j++)			scanf("%d", &mp[i][j]);	dfs(1);	printf("%d", ans);	return 0;}```