PROG-T1015: Tiling

#include <bits/stdc++.h>
using namespace std;

typedef pair<int, int> pii;

const int N = 17;

pii dir[4] = {pii(0, 1), pii(0, -1), pii(1, 0), pii(-1, 0)};
int board[N + 2][N + 2];

int BFS(int r, int c){
    queue<pii> que;
    int tr = board[r][c];
    board[r][c] = 0;
    int cnt = 1;
    que.emplace(r, c);
    while(!que.empty()){
        int ur = que.front().first;
        int uc = que.front().second;
        que.pop();
        for(int d = 0; d < 4; ++d){
            int vr = ur + dir[d].first;
            int vc = uc + dir[d].second;
            if(board[vr][vc] == tr){
                board[vr][vc] = 0;
                ++cnt;
                que.emplace(vr, vc);
            }
        }
    }
    return cnt;
}

int main(){

    int n;
    scanf("%d", &n);
    for(int i = 1; i <= n; ++i){
        for(int j = 1; j <= n; ++j){
            scanf("%d", &board[i][j]);
        }
    }

    int cnt = 0;
    for(int i = 1; i <= n; ++i){
        for(int j = 1; j <= n; ++j){
            if(board[i][j] == 0){
                continue;
            }
            int tr = board[i][j];
            bool isCandidate = false;
            if(board[i][j + 1] == tr && board[i + 1][j] == tr){
                isCandidate = true;
            } else if(board[i + 1][j - 1] == tr && board[i + 1][j] == tr){
                isCandidate = true;
            } else if(board[i][j + 1] == tr && board[i + 1][j + 1] == tr){
                isCandidate = true;
            } else if(board[i + 1][j] == tr && board[i + 1][j + 1] == tr){
                isCandidate = true;
            }
            if(BFS(i, j) == 3 && isCandidate){
                ++cnt;
            }
        }
    }
    cout << cnt;

    return 0;
}