Submission #791306

#	Time	Username	Problem	Language	Result	Execution time	Memory
791306		skittles1412	Rectangles (IOI19_rect)	C++17	72 / 100	5057 ms	442356 KiB

rect

#include "bits/extc++.h"

using namespace std;

template <typename T, typename... U>
void dbgh(const T& t, const U&... u) {
    cerr << t;
    ((cerr << " | " << u), ...);
    cerr << endl;
}

#ifdef DEBUG
#define dbg(...)                                              \
    cerr << "L" << __LINE__ << " [" << #__VA_ARGS__ << "]: "; \
    dbgh(__VA_ARGS__)
#else
#define dbg(...)
#define cerr   \
    if (false) \
    cerr
#endif

using ll = long long;

#define endl "\n"
#define long int64_t
#define sz(x) int(std::size(x))

namespace s1 {

constexpr int DIRS[4][2] {{0, 1}, {0, -1}, {-1, 0}, {1, 0}};

int n, m;
vector<vector<char>> vis;
vector<vector<int>> arr;

bool ibs(int x, int y) {
    return 0 <= x && x < n && 0 <= y && y < m;
}

template <typename Cb>
void dfs(int x, int y, const Cb& cb) {
    if (!ibs(x, y) || vis[x][y] || arr[x][y]) {
        return;
    }
    cb(x, y);
    vis[x][y] = true;
    for (auto& [dx, dy] : DIRS) {
        dfs(x + dx, y + dy, cb);
    }
}

long solve(const vector<vector<int>>& _arr) {
    arr = _arr;
    n = sz(arr);
    m = sz(arr[0]);
    vis.resize(n, vector<char>(m));

    long ans = 0;

    auto c2 = [&](long n) -> long { return n * (n - 1) / 2; };

    for (int i = 0; i < n; i++) {
        for (int j = 0; j < m; j++) {
            if (vis[i][j] || arr[i][j]) {
                continue;
            }
            int mnx = 1e9, mxx = 0, mny = 1e9, mxy = 0, cnt = 0;
            dfs(i, j, [&](int x, int y) -> void {
                mnx = min(mnx, x);
                mxx = max(mxx, x);
                mny = min(mny, y);
                mxy = max(mxy, y);
                cnt++;
            });

            if (cnt == (mxx - mnx + 1) * (mxy - mny + 1) && mnx && mny &&
                mxx < n - 1 && mxy < m - 1) {
                ans++;
            }
        }
    }

    return ans;
}

}  // namespace s1

struct PSA {
    vector<int> psum;

    PSA(const vector<int>& arr) : psum(sz(arr) + 1) {
        partial_sum(begin(arr), end(arr), psum.begin() + 1);
    }

    int query(int l, int r) const {
        return psum[r] - psum[l];
    }
};

vector<pair<int, int>> solve1(const vector<int>& arr) {
    int n = sz(arr);
    vector<pair<int, int>> ans;
    for (int i = 1; i < n - 1; i++) {
        int cmx = 0;
        for (int j = i; j < n - 1; j++) {
            cmx = max(cmx, arr[j]);
            if (arr[i - 1] > cmx && arr[j + 1] > cmx) {
                ans.emplace_back(i, j);
            }
        }
    }

    assert(sz(ans) <= 2 * n + 10);
    sort(begin(ans), end(ans));

    return ans;
}

template <typename T>
vector<T> set_inter(const vector<T>& a, const vector<T>& b) {
    vector<T> out;
    set_intersection(begin(a), end(a), begin(b), end(b), back_inserter(out));
    return out;
}

ll count_rectangles(vector<vector<int>> arr) {
    int n = sz(arr), m = sz(arr[0]);

    {
        bool ok = true;
        for (auto& a : arr) {
            for (auto& b : a) {
                ok &= 0 <= b && b <= 1;
            }
        }
        if (ok) {
            return s1::solve(arr);
        }
    }

    vector<pair<int, int>> r_res[n], c_res[m];
    for (int i = 0; i < n; i++) {
        r_res[i] = solve1(arr[i]);
    }
    for (int i = 0; i < m; i++) {
        vector<int> tmp;
        for (int j = 0; j < n; j++) {
            tmp.push_back(arr[j][i]);
        }
        c_res[i] = solve1(tmp);
    }

    vector<int> r_good[m][m];
    for (int i = 0; i < n; i++) {
        for (auto& [ql, qr] : r_res[i]) {
            r_good[ql][qr].push_back(i);
        }
    }

    long ans = 0;

    for (int cl = m - 2; cl >= 1; cl--) {
        vector<pair<int, int>> c_cur = c_res[cl];
        for (int cr = cl; cr < m - 1; cr++) {
            c_cur = set_inter(c_cur, c_res[cr]);

            vector<int> c_bad(n, 1);
            for (auto& a : r_good[cl][cr]) {
                c_bad[a] = 0;
            }
            PSA p_bad(c_bad);

            for (auto& [ql, qr] : c_cur) {
                if (!p_bad.query(ql, qr + 1)) {
                    ans++;
                }
            }
        }
    }

    return ans;
}

Compilation message (stderr)

rect.cpp: In function 'int64_t s1::solve(const std::vector<std::vector<int> >&)':
rect.cpp:61:10: warning: variable 'c2' set but not used [-Wunused-but-set-variable]
   61 |     auto c2 = [&](long n) -> long { return n * (n - 1) / 2; };
      |          ^~

• Subtask 1: 8 / 8
• Subtask 2: 7 / 7
• Subtask 3: 12 / 12
• Subtask 4: 22 / 22
• Subtask 5: 10 / 10
• Subtask 6: 13 / 13
• Subtask 7: 0 / 28