洛谷 P1219 [USACO1.5]八皇后 Checker Challenge 题解

做题地址：https://www.luogu.com.cn/problem/solution/P1219

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这一题是一道dfs问题

#include 
#include 
#include 
#include 

using namespace std;

const int N = 16;

int n;
bool col[N * N], dg[N * N], udg[N * N];
int g[N * N], res;

void dfs(int u){
    if (u == n) {
        res ++;
        if (res <= 3){
            for (int  i = 0; i < n; i ++ ) cout << g[i] + 1<< ' ';
            puts("");
            return;
        }
    }
    
    for (int i = 0; i < n; i ++ ){
        if (!col[i] && !dg[u + i] && !udg[n - u + i]){
            g[u] = i;
            col[i] = dg[u + i] = udg[i - u + n] = true;
            dfs(u + 1);
            col[i] = dg[u + i] = udg[i - u + n] = false;
        }
    }
}
int main(){
    cin >> n;
    
    dfs(0);
    
    cout << res << endl;
    return 0;
}