UVa 11953 Battleships

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

int T,N;
char grid[105][105];

int dr[]={-1,0,1,0};  //chay theo chiu kim dong ho
int dc[]={0,1,0,-1};

void floodfill(int r,int c){
    if(r<0||r>=N||c<0||c>=N ||grid[r][c]=='.') return ;
    grid[r][c]='.';
    for(int d=0;d<4;d++)
        floodfill(r+dr[d],c+dc[d]);
}

int main()
{
    // freopen("11953 in.txt","r",stdin);
    // freopen("11953 out.txt","w",stdout);

    scanf("%d",&T);
    for(int t=1;t<=T;t++){
        scanf("%d",&N);
        for(int i=0;i<N;i++)
            scanf("%s",grid[i]);


        int ans=0;
        for(int i=0;i<N;i++){
            for(int j=0;j<N;j++){
                if(grid[i][j]=='x'){
                    ans++;
                    floodfill(i,j);
                }
            }
        }
        printf("Case %d: %d\n",t,ans);
    }

    return 0;
}

//By hieudoanitus