Kattis-Problems/Islands.java at master · gsyndromes/Kattis-Problems · GitHub

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import java.io.BufferedReader;
import java.io.BufferedOutputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.util.*;


public class Islands {
    public static int dfs(char[][] picture,int[][] visited,int row, int column, int srcR, int srcC) {
        int r = row;
        int c = column;
        int sourceRow = srcR;
        int sourceC = srcC;

                if (visited[sourceRow][sourceC] == 0) {
                visited[sourceRow][sourceC] = 1;

                // int[] directionR = { -1 , 1 , 0 , 0}; // up, down, left,right
                // int[] directionC = { 0, 0, -1, 1};

                // for (int i = 0; i < 4; i++) {
                //     int x = srcR + directionR[i];
                //     int y = srcC + directionC[i];
                //     if ( x < 0 || y < 0 || x >= r || y >= c) {
                //         continue;
                //     }

                //     if (( picture[x][y] == 'C' || picture[x][y] == 'L') && visited[x][y] == 0 ) {
                //         dfs(picture,visited,r,c,x,y);
                //     }


                // }


                    if ( (!(sourceC + 1 >= c)) && (visited[srcR][sourceC+1] == 0) && (picture[srcR][sourceC+1] == 'C' || picture[srcR][sourceC+1] == 'L')) { //go right
                        dfs(picture,visited,r,c,srcR,sourceC+1);
                    }
                    if ((!(sourceC - 1 < 0)) && (visited[srcR][sourceC-1] == 0) && (picture[srcR][sourceC-1] == 'C' || picture[srcR][sourceC-1] == 'L')) { //go left
                        dfs(picture,visited,r,c,srcR,sourceC-1);
                     }
                     if ((!(srcR - 1 < 0)) && (visited[srcR - 1][sourceC] == 0) && (picture[srcR - 1][sourceC] == 'C' || picture[srcR-1][sourceC] == 'L')) { //go up
                        dfs(picture,visited,r,c,srcR-1,sourceC);
                    }
                     if ((!(srcR + 1 >= r)) && (visited[srcR+1][sourceC] == 0) && (picture[srcR+1][sourceC] == 'C' || picture[srcR+1][sourceC] == 'L')) { //go down
                        dfs(picture,visited,r,c,srcR+1,sourceC);
                 }
        }
        return 0;
    }


    public static void main(String[] args) {
        FastIO fio = new FastIO();

        int r = fio.nextInt();
        int c = fio.nextInt();
        char[][] image = new char[r][c];
        int[][] visited = new int[r][c];
        int counter = 0;

        for(int i = 0; i < r ; i ++) {
            char[] temp = fio.nextLine().toCharArray();
            for (int j = 0; j < c; j++) {
                image[i][j] = temp[j];
                visited[i][j] = 0;
            }

        }

        for ( int i = 0; i < r ; i ++) {
            for (int j = 0; j < c ; j ++) {
            if (image[i][j] == 'L' && visited[i][j] == 0) {
                dfs(image,visited,r,c,i,j);
                counter++;
            }
        }
    }

        fio.print(counter);
        fio.close();


    }
}
/**
 * Fast I/O
 * @source https://www.geeksforgeeks.org/fast-io-in-java-in-competitive-programming/
 */
class FastIO extends PrintWriter
{
    BufferedReader br;
    StringTokenizer st;

    public FastIO()
    {
        super(new BufferedOutputStream(System.out));
        br = new BufferedReader(new
                InputStreamReader(System.in));
    }

    String next()
    {
        while (st == null || !st.hasMoreElements())
        {
            try
            {
                st = new StringTokenizer(br.readLine());
            }
            catch (IOException  e)
            {
                e.printStackTrace();
            }
        }
        return st.nextToken();
    }

    int nextInt()
    {
        return Integer.parseInt(next());
    }

    long nextLong()
    {
        return Long.parseLong(next());
    }

    double nextDouble()
    {
        return Double.parseDouble(next());
    }

    String nextLine()
    {
        String str = "";
        try
        {
            str = br.readLine();
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }
        return str;
    }
}