P1219 [USACO1.5]八皇后 Checker Challenge

// Problem: P1219 [USACO1.5]八皇后 Checker Challenge
// Contest: Luogu
// URL: https://www.luogu.com.cn/problem/P1219
// Memory Limit: 125 MB
// Time Limit: 1000 ms
// User: Pannnn
 
#include <bits/stdc++.h>
 
using namespace std;
 
template<class T>
void debugVector(const T &a) {
    cout << "[ ";
    for (size_t i = 0; i < a.size(); ++i) {
        cout << a[i] << (i == a.size() - 1 ? " " : ", ");
    }
    cout << "]" << endl;
}
 
template<class T1, class T2>
void debugVectorPair(const vector<pair<T1, T2>> &a) {
    cout << "{";
    for (size_t i = 0; i < a.size(); ++i) {
        cout << "[ " << a[i].first << ": " << a[i].second << (i == a.size() - 1 ? " ]" : " ], ");
    }
    cout << "}" << endl;
}
 
 
template<class T>
void debugMatrix2(const T &a) {
    for (size_t i = 0; i < a.size(); ++i) {
        debugVector(a[i]);
    }
}
 
template<class T>
using matrix2 = vector<vector<T>>;
 
template<class T>
vector<vector<T>> getMatrix2(size_t n, size_t m, T init = T()) {
    return vector<vector<T>>(n, vector<T>(m, init));
}
 
template<class T>
using matrix3 = vector<vector<vector<T>>>;
 
template<class T>
vector<vector<vector<T>>> getMatrix3(size_t x, size_t y, size_t z, T init = T()) {
    return vector<vector<vector<T>>>(x, vector<vector<T>>(y, vector<T>(z, init)));
}
 
vector<int> genBigInteger(const string &a) {
    vector<int> res;
    if (a.empty()) return res;
    for (int i = a.size() - 1; i >= 0; --i) {
        res.push_back(a[i] - '0');
    }
    return res;
}
 
ostream &printBigInteger(const vector<int> &a) {
    if (a.empty()) return cout;
    for (int i = a.size() - 1; i >= 0; --i) {
        cout << a[i];
    }
    return cout;
}
 
vector<int> maxBigInteger(const vector<int> &a, const vector<int> &b) {
    if (a.size() > b.size()) {
        return a;
    } else if (a.size() < b.size()) {
        return b;
    }
    for (int i = a.size() - 1; i >= 0; --i) {
        if (a[i] > b[i]) {
            return a;
        } else if (a[i] < b[i]) {
            return b;
        }
    }
    return a;
}
 
vector<int> addBigInteger(const vector<int> &a, const vector<int> &b) {
    vector<int> res;
    int pre = 0;
    for (size_t i = 0; i < a.size() || i < b.size() || pre; ++i) {
        if (i < a.size()) pre += a[i];
        if (i < b.size()) pre += b[i];
        res.push_back(pre % 10);
        pre /= 10;
    }
    while (res.size() > 1 && res.back() == 0) {
        res.pop_back();
    }
    return res;
}
 
vector<int> mulBigInteger(const vector<int> &a, int b) {
    vector<int> res;
    int pre = 0;
    for (size_t i = 0; i < a.size() || pre; ++i) {
        if (i < a.size()) pre += a[i] * b;
        res.push_back(pre % 10);
        pre /= 10;
    }
    while (res.size() > 1 && res.back() == 0) {
        res.pop_back();
    }
    return res;
}
 
vector<int> divBigInteger(const vector<int> &a, int b, int &r) {
    vector<int> res;
    for (int i = a.size() - 1; i >= 0; --i) {
        r = 10 * r + a[i];
        res.push_back(r / b);
        r %= b;
    }
    reverse(res.begin(), res.end());
    while (res.size() > 1 && res.back() == 0) {
        res.pop_back();
    }
    return res;
}
 
void dfs(matrix2<int> &res, vector<int> &flag1, vector<int> &flag2, vector<int> &flag3, 
         vector<int> &tRes, int pos, int n) {
    if (pos > n) {
        res.push_back(tRes);
        return;
    }
    
    for (int i = 1; i <= n; ++i) {
        // 当前列已经有元素
        if (flag1[i]) {
            continue;
        }
        // 与主对角线平行的对角线上已经有元素 此时x - y == i - pos 为了去除负数，加上n
        if (flag2[i - pos + n]) {
            continue;
        }
        // 与副对角线平行的对角线上已经有元素 此时 x + y == i + pos
        if (flag3[i + pos]) {
            continue;
        }
        tRes[pos] = i;
        flag1[i] = 1;
        flag2[i - pos + n] = 1;
        flag3[i + pos] = 1;
        dfs(res, flag1, flag2, flag3, tRes, pos + 1, n);
        flag1[i] = 0;
        flag2[i - pos + n] = 0;
        flag3[i + pos] = 0;
    }
}
 
int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);
    
    int n;
    cin >> n;
    
    vector<int> flag1(n + 1);
    vector<int> flag2(2 * n + 2);
    vector<int> flag3(2 * n + 1);
    matrix2<int> res = getMatrix2<int>(0, n);
    vector<int> tRes(n + 1);
    
    dfs(res, flag1, flag2, flag3, tRes, 1, n);
    
    for (int i = 0; i < res.size() && i < 3; ++i) {
        for (int j = 1; j < res[i].size(); ++j) {
            cout << res[i][j] << " ";
        }
        cout << endl;
    }
    cout << res.size() << endl;
    return 0;
}