Submission #1202471

#	Time	Username	Problem	Language	Result	Execution time	Memory
1202471		LucaIlie	Rectangles (IOI19_rect)	C++20	37 / 100	1816 ms	1114112 KiB

rect

#include "rect.h"
#include <bits/stdc++.h>

using namespace std;

struct rect {
    int l1, c1, l2, c2;

    bool operator < (const rect &x) const {
        if (l1 == x.l1) {
            if (c1 == x.c1) {
                if (l2 == x.l2)
                    return c2 < x.c2;
                return l2 < x.l2;
            }
            return c1 < x.c1;
        }
        return l1 < x.l1;
    }

    bool operator == (const rect &x) const {
        if (x < *this)
            return false;
        if (*this < x)
            return false;
        return true;
    }
};

const int MAX_N = 2500;
const int INF = 1e9;
int n, m;
long long ans = 0;
int mat[MAX_N + 2][MAX_N + 2];
int leftG[MAX_N + 2][MAX_N + 2], leftGE[MAX_N + 2][MAX_N + 2];
int rightG[MAX_N + 2][MAX_N + 2], rightGE[MAX_N + 2][MAX_N + 2];
int upG[MAX_N + 2][MAX_N + 2], upGE[MAX_N + 2][MAX_N + 2];
int downG[MAX_N + 2][MAX_N + 2], downGE[MAX_N + 2][MAX_N + 2];
vector<int> l2s[MAX_N + 2][MAX_N + 2];
vector<int> c2s[MAX_N + 2][MAX_N + 2];
vector<rect> cand;
vector<int> st;

void init() {
    for (int l = 1; l <= n; l++) {
        mat[l][0] = INF;
        st.clear();
        st.push_back(0);
        for (int c = 1; c <= m; c++) {
            while (mat[l][c] > mat[l][st.back()]) 
                st.pop_back();
            leftGE[l][c] = st.back();
            st.push_back(c);
        }
        st.clear();
        st.push_back(0);
        for (int c = 1; c <= m; c++) {
            while (mat[l][c] >= mat[l][st.back()]) 
                st.pop_back();
            leftG[l][c] = st.back();
            st.push_back(c);
        }

        mat[l][m + 1] = INF;
        st.clear();
        st.push_back(m + 1);
        for (int c = m; c >= 1; c--) {
            while (mat[l][c] > mat[l][st.back()]) 
                st.pop_back();
            rightGE[l][c] = st.back();
            st.push_back(c);
        }
        st.clear();
        st.push_back(m + 1);
        for (int c = m; c >= 1; c--) {
            while (mat[l][c] >= mat[l][st.back()]) 
                st.pop_back();
            rightG[l][c] = st.back();
            st.push_back(c);
        }
    }

    for (int c = 1; c <= m; c++) {
        mat[0][c] = INF;
        st.clear();
        st.push_back(0);
        for (int l = 1; l <= n; l++) {
            while (mat[l][c] > mat[st.back()][c])
                st.pop_back();
            upGE[l][c] = st.back();
            st.push_back(l);
        }
        st.clear();
        st.push_back(0);
        for (int l = 1; l <= n; l++) {
            while (mat[l][c] >= mat[st.back()][c])
                st.pop_back();
            upG[l][c] = st.back();
            st.push_back(l);
        }
        
        mat[n + 1][c] = INF;
        st.clear();
        st.push_back(n + 1);
        for (int l = n; l >= 1; l--) {
            while (mat[l][c] > mat[st.back()][c])
                st.pop_back();
            downGE[l][c] = st.back();
            st.push_back(l);
        }
        st.clear();
        st.push_back(n + 1);
        for (int l = n; l >= 1; l--) {
            while (mat[l][c] >= mat[st.back()][c])
                st.pop_back();
            downG[l][c] = st.back();
            st.push_back(l);
        }
    }
}

void solve1() {

    init();

    for (int l1 = 1; l1 <= n; l1++) {
        for (int c1 = 1; c1 <= m; c1++) {
            int c2 = rightGE[l1 + 1][c1], l2 = downGE[l1][c1 + 1];
            for (int l2 = l1; l2 <= n; l2++) {
                for (int c2 = c1; c2 <= m; c2++) { 
                    if (l2 > n || c2 > m || l2 - l1 <= 1 || c2 - c1 <= 1)
                        continue;


                    bool ok = true;
                    for (int l = l1 + 1; l <= l2 - 1 && ok; l++) 
                        ok &= (rightGE[l][c1] == c2 || (leftGE[l][c2] == c1));
                    for (int c = c1 + 1; c <= c2 - 1 && ok; c++) 
                        ok &= (downGE[l1][c] == l2 || (upGE[l2][c] == l1));

                    /*
                    if (ok)
                        printf("%d %d %d %d\n\n", l1, c1, l2, c2);
                    */

                    ans += ok;
                }
            }
        }
    }
}

void solve2() {
    init();
    for (auto x: cand) {
        int l1 = x.l1, l2 = x.l2, c1 = x.c1, c2 = x.c2;

        if (l1 < 1 || c1 < 1 || l2 > n || c2 > m || l2 - l1 <= 1 || c2 - c1 <= 1)
            continue;


        //printf("%d %d %d %d\n\n", l1, c1, l2, c2);
        bool ok = true;
        for (int l = l1 + 1; l <= l2 - 1 && ok; l++) 
            ok &= (rightGE[l][c1] == c2 || (leftGE[l][c2] == c1));
        for (int c = c1 + 1; c <= c2 - 1 && ok; c++) 
            ok &= (downGE[l1][c] == l2 || (upGE[l2][c] == l1));

        /*
        if (ok)
            printf("%d %d %d %d\n\n", l1, c1, l2, c2);
        */

        ans += ok;
    }
}
        

long long count_rectangles(vector<vector<int>> a) {
    n = a.size(), m = a[0].size();

    for (int l = 1; l <= n; l++) {
        for (int c = 1; c <= m; c++) 
            mat[l][c] = a[l - 1][c - 1];
    }

    init();
    for (int l = 1; l <= n; l++) {
        for (int c = 1; c <= m; c++) {
            l2s[upGE[l][c]][c - 1].push_back(l);
            c2s[l - 1][leftGE[l][c]].push_back(c);
        }
    }
    for (int l = 1; l <= n; l++) {
        for (int c = 1; c <= m; c++) {
            l2s[l][c].push_back(downGE[l][c + 1]);
            c2s[l][c].push_back(rightGE[l + 1][c]);
            for (int l2: l2s[l][c]) {
                for (int c2: c2s[l][c])
                    cand.push_back({l, c, l2, c2});
            }
        }
    }

    sort(cand.begin(), cand.end());
    cand.resize(unique(cand.begin(), cand.end()) - cand.begin());

    //solve1();
    solve2();

    return ans;
}

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