题解

#include <bits/stdc++.h>
using namespace std;
struct node{
	int a[15] = {0}, ct = 0;
	bool vis[15] = {0};
};
int n = 8;
bool check(node n){
	for(int i = 1; i < n.ct; i++){
		if(n.a[i] + i == n.a[n.ct] + n.ct || n.a[i] - i == n.a[n.ct] - n.ct){
			return 0;//如果在对角线就不行
		}
	}
	return 1;
}
int bfs(int n){
	int ct = 0;
	node xxx; 
	queue <node> q;
	q.push(xxx);
	while(!q.empty()){
		node head = q.front();
		q.pop();
		if(head.ct == n){
			ct++;
			if(ct <= 3){
				for(int i = 1; i <= n; i++) cout << head.a[i] << ' ';//输出
				cout << endl;
			}
			continue;
		}for(int i = 1; i <= n; i++){
			if(!head.vis[i]){
				node xx = head;
				xx.a[++xx.ct] = i;
				if(check(xx)){
					xx.vis[i] = 1;
					q.push(xx);
				}
			}
		}
	}return ct;
}
int main(){
	cin >> n;
	cout << bfs(n);
	return 0;
}