PROG-1015: Tiling

#include <bits/stdc++.h>

using namespace std;
using pii = pair<int, int>;
int n;
int ar[20][20];
bool visited[20][20];
int dx[] = {1, -1, 0, 0};
int dy[] = {0, 0, 1, -1};

bool position(int i,int j){
    return i >= 1 and i <= n and j >= 1 and j <= n;
}

void fill_visited(int ui, int uj){
    queue <pii> q;
    q.push({ui,uj});
    while(q.size()>0){
        ui = q.front().first;
        uj = q.front().second;
        q.pop();
        if(!visited[ui][uj])
            continue;
        visited[ui][uj] = false;
        for(int d=0;d<4;d++){
            int vi = ui+dx[d];
            int vj = uj+dy[d];
            if(position(vi,vj) and ar[vi][vj] == ar[ui][uj] and visited[vi][vj])
                q.push({vi,vj});
        }
    }
}

int count_num(int i, int j, int cmp){
    int cnt = 0;
    queue <pii> q;
    q.push({i,j});
    while(q.size()>0){
        int ui,uj;
        ui = q.front().first;
        uj = q.front().second;
        q.pop();
        if(visited[ui][uj])
            continue;
        visited[ui][uj] = true;
        cnt ++;
        for(int d=0;d<4;d++){
            int vi,vj;
            vi = ui+dx[d];
            vj = uj+dy[d];
            if(position(vi,vj) and ar[vi][vj] == cmp and !visited[vi][vj]){
                q.push({vi,vj});
            }
        }
    }
    if(cnt == 3) fill_visited(i,j);
    return cnt;
}

int around(int ui,int uj){
    int u = ui-1;
    int d = ui+1;
    int l = uj-1;
    int r = uj+1;
    if(position(u, l) and ar[ui][uj] == ar[u][uj] and ar[ui][uj] == ar[ui][l]) return true;
    if(position(u, r) and ar[ui][uj] == ar[u][uj] and ar[ui][uj] == ar[ui][r]) return true;
    if(position(d, r) and ar[ui][uj] == ar[d][uj] and ar[ui][uj] == ar[ui][r] ) return true;
    if(position(d, l) and ar[ui][uj] == ar[d][uj] and ar[ui][uj] == ar[ui][l] ) return true;
    return false;
}

int main(){

    scanf("%d", &n);

    int ans = 0;
    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            scanf("%d", &ar[i][j]);
        }
    }

    for(int i=1;i<=n;i++){
        for(int j=1;j<=n;j++){
            if(ar[i][j] == 0) continue;
            if(count_num(i, j, ar[i][j]) == 3 and around(i, j))
                ans++;
        }
    }

    printf("%d", ans);

    return 0;
}