C++ Program to Find all rectangles filled with 0

// C++ program for the above approach

#include <bits/stdc++.h>

using namespace std;

void findend(int i, int j, vector<vector<int> >& a,
             vector<vector<int> >& output, int index)
{
    int x = a.size();
    int y = a[0].size();

    // flag to check column edge case,
    // initializing with 0
    int flagc = 0;

    // flag to check row edge case,
    // initializing with 0
    int flagr = 0;
    int n, m;

    for (m = i; m < x; m++) {

        // loop breaks where first 1 encounters
        if (a[m][j] == 1) {
            flagr = 1; // set the flag
            break;
        }

        // pass because already processed
        if (a[m][j] == 5)
            continue;

        for (n = j; n < y; n++) {
            // loop breaks where first 1 encounters
            if (a[m][n] == 1) {
                flagc = 1; // set the flag
                break;
            }

            // fill rectangle elements with any
            // number so that we can exclude
            // next time
            a[m][n] = 5;
        }
    }

    if (flagr == 1)
        output[index].push_back(m - 1);
    else
        // when end point touch the boundary
        output[index].push_back(m);

    if (flagc == 1)
        output[index].push_back(n - 1);
    else
        // when end point touch the boundary
        output[index].push_back(n);
}

void get_rectangle_coordinates(vector<vector<int> > a)
{

    // retrieving the column size of array
    int size_of_array = a.size();

    // output array where we are going
    // to store our output
    vector<vector<int> > output;

    // It will be used for storing start
    // and end location in the same index
    int index = -1;

    for (int i = 0; i < size_of_array; i++) {
        for (int j = 0; j < a[0].size(); j++) {
            if (a[i][j] == 0) {

                // storing initial position
                // of rectangle
                output.push_back({ i, j });

                // will be used for the
                // last position
                index = index + 1;
                findend(i, j, a, output, index);
            }
        }
    }

    cout << "[";
    int aa = 2, bb = 0;

    for (auto i : output) {
        bb = 3;
        cout << "[";
        for (int j : i) {
            if (bb)
                cout << j << ", ";
            else
                cout << j;
            bb--;
        }
        cout << "]";
        if (aa)
            cout << ", ";
        aa--;
    }
    cout << "]";
}

// Driver code
int main()
{
    vector<vector<int> > tests = {
        { 1, 1, 1, 1, 1, 1, 1 }, { 1, 1, 1, 1, 1, 1, 1 },
        { 1, 1, 1, 0, 0, 0, 1 }, { 1, 0, 1, 0, 0, 0, 1 },
        { 1, 0, 1, 1, 1, 1, 1 }, { 1, 0, 1, 0, 0, 0, 0 },
        { 1, 1, 1, 0, 0, 0, 1 }, { 1, 1, 1, 1, 1, 1, 1 }
    };

    get_rectangle_coordinates(tests);

    return 0;
}

// This code is contributed by mohit kumar 29.