Submission #408871

#	Time	Username	Problem	Language	Result	Execution time	Memory
408871		idk321	Rectangles (IOI19_rect)	C++17	13 / 100	419 ms	159948 KiB

rect

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

using namespace std;
typedef long long ll;

vector<vector<int>> a;
int n, m;

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

    bool allSmall = true;
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < m; j++)
        {
            if (a[i][j] > 1) allSmall = false;
        }
    }

    if (allSmall)
    {
        vector<vector<int>> left(n, vector<int>(m));
        vector<vector<int>> down(n, vector<int>(m));
        vector<vector<int>> pref(n + 1, vector<int>(m + 1));
        for (int i = 1; i <= n; i++)
        {
            int sum = 0;
            for (int j = 1; j <= m; j++)
            {
                sum += a[i - 1][j - 1];
                pref[i][j] = pref[i - 1][j] + sum;
            }
        }

        for (int i = 1; i < n - 1; i++)
        {
            for (int j = m - 2; j >= 1; j--)
            {
                if (j == m - 2)
                {
                    left[i][j] = j;
                } else
                {
                    if (a[i][j + 1] == 1)
                    {
                        left[i][j] = j;
                    } else
                    {
                        left[i][j] = left[i][j + 1];
                    }
                }
            }
        }

        for (int j = 1; j < m - 1; j++)
        {
            for (int i = n - 2; i >= 1; i--)
            {
                if (i == n - 2)
                {
                    down[i][j] = i;
                } else
                {
                    if (a[i + 1][j] == 1)
                    {
                        down[i][j] = i;
                    } else
                    {
                        down[i][j] = down[i + 1][j];
                    }
                }
            }
        }

        int res = 0;
        for (int i = 1; i < n - 1; i++)
        {
            for (int j = 1; j < m - 1; j++)
            {
                int i2 = down[i][j];
                int j2 = left[i][j];

                int sum1 = pref[i2 + 1][j2 + 1] - pref[i2 + 1][j] - pref[i][j2 + 1] + pref[i][j];
                int sum2 = pref[i2 + 2][j2 + 2] - pref[i2 + 2][j - 1] - pref[i - 1][j2 + 2] + pref[i - 1][j - 1];
                sum2 -= a[i2 + 1][j2 + 1];
                sum2 -= a[i2 + 1][j - 1];
                sum2 -= a[i - 1][j2 + 1];
                sum2 -= a[i - 1][j - 1];
                if (sum1 == 0 && sum2 == (i2 - i + 1) * 2 + (j2 - j + 1) * 2) res++;
            }
        }

        return res;
    }
	return 1;
}

/*
5 5
0 1 1 1 0
1 0 1 0 1
1 0 1 0 1
1 0 1 0 1
0 1 1 1 0


*/

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