PROG-1015: Tiling

#include<stdio.h>
#include<queue>
using namespace std;
int n;

int board[20][20];
bool visited[20][20];

void clearvisited(){
    for(int i = 0 ; i < 20 ; i ++)for(int j = 0 ; j < 20 ; j ++)visited[i][j] = false;
}
struct pos{
    int I,J;
};

int moveI[4] = {-1,0,1,0};
int moveJ[4] = {0,1,0,-1};

bool IsInB(int I,int N){
    return (0 <= I && I < N);
}
int cntcom(int I,int J){
    int key = board[I][J];
    queue<pos> q;
    clearvisited();
    int cnt = 0;
    q.push({I,J});
    while(!q.empty()){
        int uI = q.front().I;
        int uJ = q.front().J;
        q.pop();
        if(visited[uI][uJ])continue;
        cnt ++;
        visited[uI][uJ] = true;
        for(int i = 0 ; i < 4 ; i ++){
            int vI = uI + moveI[i];
            int vJ = uJ + moveJ[i];
            if(IsInB(vI,n) && IsInB(vJ,n) && !visited[vI][vJ] && board[vI][vJ] == key){
                q.push({vI,vJ});
            }
        }
    }
    return cnt;
}
void erase(int I,int J){
    int key = board[I][J];
    queue<pos> q;
    clearvisited();
    q.push({I,J});
    while(!q.empty()){
        int uI = q.front().I;
        int uJ = q.front().J;
        q.pop();
        if(visited[uI][uJ])continue;
        board[uI][uJ] = 0;
        visited[uI][uJ] = true;
        for(int i = 0 ; i < 4 ; i ++){
            int vI = uI + moveI[i];
            int vJ = uJ + moveJ[i];
            if(IsInB(vI,n) && IsInB(vJ,n) && !visited[vI][vJ] && board[vI][vJ] == key){
                q.push({vI,vJ});
            }
        }
    }
}
bool minicheck(int I,int J){
    int key = board[I][J];

    int TypeA1I[4] = {0,-1,0,-1};
    int TypeA1J[4] = {1,0,-1,0};

    int TypeA2I[4] = {1,0,1,0};
    int TypeA2J[4] = {0,-1,0,1};

    for(int i = 0 ; i < 4 ; i ++){
        pos A1;
        pos A2;
        A1.I = I + TypeA1I[i];
        A1.J = J + TypeA1J[i];
        A2.I = I + TypeA2I[i];
        A2.J = J + TypeA2J[i];

        if(IsInB(A1.I,n) && IsInB(A1.J,n) && IsInB(A2.I,n) && IsInB(A2.J,n)){
            if(board[I][J] == board[A1.I][A1.J] && board[I][J] == board[A2.I][A2.J])return true;
        }
    }
    return false;
}
int check(int I,int J){
    int key = board[I][J];
    queue<pos> q;
    clearvisited();
    q.push({I,J});

    pos arr[3];
    int idx = 0;
    while(!q.empty()){
        int uI = q.front().I;
        int uJ = q.front().J;
        q.pop();
        if(visited[uI][uJ])continue;
        arr[idx++] = {uI,uJ};
        visited[uI][uJ] = true;
        for(int i = 0 ; i < 4 ; i ++){
            int vI = uI + moveI[i];
            int vJ = uJ + moveJ[i];
            if(IsInB(vI,n) && IsInB(vJ,n) && !visited[vI][vJ] && board[vI][vJ] == key){
                q.push({vI,vJ});
            }
        }
    }

    for(int i = 0 ; i < 3 ; i ++){
        if(minicheck(arr[i].I,arr[i].J))return 1;
    }
    return 0;
}

int main()
{
    scanf("%d",&n);
    for(int i = 0 ; i < n ; i ++){
        for(int j = 0 ; j < n ; j ++){
            scanf("%d",&board[i][j]);
        }
    }
    int ans = 0;
    for(int i = 0 ; i < n ; i ++){
        for(int j = 0 ; j < n ; j ++){
            if(board[i][j] == 0)continue;
            if(cntcom(i,j) != 3){
                erase(i,j);
                continue;
            }
            else{
                ans += check(i,j);
                erase(i,j);
            }
        }
    }
    printf("%d",ans);
    return 0;
}