Square Detector

SquareDetector

#include <vector>
#include <iostream>
#include <string>
using namespace std;
 
int main()
{
    int kase;
    cin>> kase;
    for (int k = 1; k <= kase; k++)
    {
        int n;
        cin >> n;
        vector<vector<int> > vec(n);
        for (int i = 0; i < n; i++)
        {
            vec[i].resize(n);
        }
        int first_x = -1;
        int first_y = -1;
        bool found_black = false;
        // init and look for the first black
        for (int i = 0; i < n; i++)
        {
            string line;
            cin >> line;
            for (int j = 0; j < n; j++) {
                if (line[j] == '#')
                {
                    vec[i][j] = 1;
                    if (!found_black)
                    {
                        first_x = i;
                        first_y = j;
                        found_black = true;
                    }
                }
                else
                {
                    vec[i][j] = 0;
                }
            }
        }
        if (!found_black)
        {
            cout << "Case #" << k << ": NO" << endl;
        }
        // get the len of the square
        int len = 0;
        for (int j = first_y; j < n; j++)
        {
            if (vec[first_x][j] == 1)
                len++;
            else
                break;
        }
        // go through the matrix and to hit testing
        bool valid = true;
        for (int i = 0; i < n && valid; i++)
        {
            for (int j = 0; j < n && valid; j++)
            {
                if (i < first_x || j < first_y
                    || i >= first_x + len || j >= first_y + len) // outside
                {
                    if (vec[i][j] == 1)
                    {
                        valid = false;
                    }
                }
                else if (vec[i][j] == 0)
                {
                    valid = false;
                }
            }
        }
        if (!valid)
        {
            cout << "Case #" << k << ": NO" << endl;
        }
        else
        {
            cout << "Case #" << k << ": YES" << endl;
        }
    }
}