HackerEarth Valid Chess Board problem solution

In this HackerEarth Valid Chess Board problem solution, you are given a tiled chart paper of N rows and M columns. There are a total of N x M tiles in it. Each tile is colored either black or white. Now, you need to count how many ways are there to cut valid chessboards of size 8 x 8 out of this chart paper.

HackerEarth Valid Chess Board problem solution.

#include<bits/stdc++.h>
#define LL long long int
#define M 1000000007
#define endl "\n"
#define eps 0.00000001
LL pow(LL a,LL b,LL m){ a%=m;LL x=1,y=a;while(b > 0){if(b%2 == 1){x=(x*y);if(x>m) x%=m;}y = (y*y);if(y>m) y%=m;b /= 2;}return x%m;}
LL gcd(LL a,LL b){if(b==0) return a; else return gcd(b,a%b);}
LL gen(LL start,LL end){LL diff = end-start;LL temp = rand()%start;return temp+diff;}
using namespace std;
char a[1001][1001];
int f(int x1,int y1,int x2,int y2)  {
    for(int i = x1; i <= x2; i++)   {
        for(int j = y1 + 1; j <= y2; j++)   {
            if(a[i][j] == a[i][j - 1])  {
                return 0;
            }
        }
    }
    for(int j = y1; j <= y2; j++)   {
        for(int i = x1 + 1; i <= x2; i++)   {
            if(a[i][j] == a[i - 1][j])  {
                return 0;
            }
        }
    }
    return 1;
}
int main()  {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n, m;
    cin >> n >> m;
    for(int i = 0; i < n; i++)  {
        for(int j = 0; j < m; j++)  {
            cin >> a[i][j];
        }
    }
    int ans = 0;
    for(int i = 0; i < n; i++)  {
        for(int j = 0; j < m; j++)  {
            if(i + 8 <= n && j + 8 <= m) {
                ans = ans + f(i , j , i + 7 , j + 7);
            }
        }
    }
    cout << ans;
}

Second solution

#include <bits/stdc++.h>

using namespace std;

const int N = 1E3 + 5;
string mat[N];

bool f(int x, int y, int n, int m) {
    for(int i = x; i < x + 8; i ++) {
        for(int j = y; j < y + 7; j ++) {
            if(mat[i][j] == mat[i][j + 1] || (i < x + 7 && mat[i][j] == mat[i + 1][j]))
                return 0;
        }
    }
    return 1;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int n, m;
    cin >> n >> m;
    for(int i = 0; i < n; i ++)
        cin >> mat[i];
    int cnt = 0;
    for(int i = 0; i < n; i ++) {
        for(int j = 0; j < m; j ++) {
            if(i + 8 <= n && j + 8 <= m && f(i, j, n, m))
                cnt ++;
        }
    }
    cout << cnt;
    return 0;
}