queens(all solutions)(map NxN with N queens)

#include<bits/stdc++.h>
#define spc << ' ' <<
#define spce << ' '
#define ele << '\n'
#define el << '\n' <<
#define cout cout <<
#define INF 99999
#define AINF -99999
#define ULINT unsigned long long int
#define LINT long long int
using namespace std;
template<typename tmp>
void output(vector<tmp>& vc, char en = ' ') {
    for (tmp x : vc)
        cout x << en;
}
template<typename tmp>
void input(vector<tmp>& vc) {
    for (tmp& x : vc)
        cin >> x;
}

bool cmax(int&, int);
bool cmin(int&, int);
int bit_degree(int, int);
int nod(int, int);
int c = 0;
int l = 8;
vector<pair<int, int> > taken;
set<vector<pair<int, int> > > s;
char* mt;
char* mp(int x, int y) {
    return &mt[x + y * l];
}
void paint_up(int x, int y) {
    taken.push_back({x, y});
    *mp(x, y) += 1;
    for (int i = 0; i < x; ++i)
        *mp(i, y) += 1;
    for (int i = x + 1; i < l; ++i)
        *mp(i, y) += 1;
    for (int i = 0; i < y; ++i)
        *mp(x, i) += 1;
    for (int i = y + 1; i < l; ++i)
        *mp(x, i) += 1;
    for (int i = 1; y - i >= 0 && x - i >= 0; ++i)
        *mp(x - i, y - i) += 1;
    for (int i = 1; y + i < l && x + i < l; ++i)
        *mp(x + i, y + i) += 1;
    for (int i = 1; y - i >= 0 && x + i < l; ++i)
        *mp(x + i, y - i) += 1;
    for (int i = 1; y + i < l && x - i >= 0; ++i)
        *mp(x - i, y + i) += 1;
}
void remove_paint() {
    int x, y;
    x = (*(taken.end() - 1)).first;
    y = (*(taken.end() - 1)).second;
    *mp(x, y)-= 1;
    for (int i = 0; i < x; ++i)
        *mp(i, y) -= 1;
    for (int i = x + 1; i < l; ++i)
        *mp(i, y) -= 1;
    for (int i = 0; i < y; ++i)
        *mp(x, i) -= 1;
    for (int i = y + 1; i < l; ++i)
        *mp(x, i) -= 1;
    for (int i = 1; y - i >= 0 && x - i >= 0; ++i)
        *mp(x - i, y - i) -= 1;
    for (int i = 1; y + i < l && x + i < l; ++i)
        *mp(x + i, y + i) -= 1;
    for (int i = 1; y - i >= 0 && x + i < l; ++i)
        *mp(x + i, y - i) -= 1;
    for (int i = 1; y + i < l && x - i >= 0; ++i)
        *mp(x - i, y + i) -= 1;
    taken.pop_back();
}
bool take_next(int num = 8) {
    if (num == 0) {
        sort(taken.begin(), taken.end());
        s.insert(taken);
        return true;
    }
    auto t = find(mt, mt + l * l, 0);
    while (t != mt + l * l) {
        int tmp = t - mt;
        paint_up(tmp % l, tmp / l);
        bool tb = take_next(num - 1);
        if (tb && num != l) {
            remove_paint();
            return tb;
        } else {
            remove_paint();
            t = find(t + 1, mt + l * l, 0);
        }
    }
    return false;
}
int main() {
    cin >> l;
    mt = new char[l * l];
    for (int i = 0; i < l * l; ++i)
        mt[i] = 0;
    take_next(l);
    int c = 0;
    if (s.size())
        for_each(s.begin(), s.end(), [&c](vector<pair<int, int> > ta){cout ++c << ':' ele; for (auto x : ta) cout char(int('a') + x.first) << x.second + 1 spce; cout '\n'; });
    else
        cout "No answer";
}

int nod(int a, int b) {
    return b ? nod(b, a % b) : a;
}

bool cmax(int& a, int b) {
    if (a >= b)
        return false;
    else {
        a = b;
        return true;
    }
}

bool cmin(int& a, int b) {
    if (a <= b)
        return false;
    else {
        a = b;
        return true;
    }
}

int bit_degree(int a, int b) {
    if (b != 1)
        if (!(b % 2)) {
            b /= 2;
            int tmp = bit_degree(a, b);
            return tmp * tmp;
        } else {
            b--;
            return (bit_degree(a, b) * a);
        }
    else
        return a;
}