Uva 572 Oil Deposits

思路：可以用DFS求解。遍历这个二维数组，没发现一次未被发现的‘@’，便将其作为起点进行搜索。最后的答案，是这个遍历过程中发现了几次为被发现的‘@’

import java.util.*;



public class Main{



    public static void main(String[] args) {

        Scanner in = new Scanner( System.in );

        while( true ) {

            int rows, cols;

            rows = in.nextInt(); // read the rows

            cols = in.nextInt(); // read the cols

            if( rows == 0 && cols == 0 ) { // the input end

                break;

            }

            OilDeposits od = new OilDeposits( rows, cols );

            od.readGrids( in ); // read the strings

            System.out.println( od.getPocketsAmount() );

        }

    }

}



class OilDeposits{

    private int rows, cols;

    private char grids[][];

    private boolean vis[][];

    private final int dir[][] = { // the eight directions

            {-1,-1}, {-1,0}, {-1,1}, {0,-1}, {0,1}, {1,-1}, {1,0}, {1,1}

        };



    private final char EMPTY = '*';

    private final char EXIST = '@';

    

    public OilDeposits( int rows, int cols ) {

        this.rows = rows;

        this.cols = cols;

        this.grids = new char[ rows + 5 ][ cols + 5 ];

        this.vis = new boolean[ rows ][ cols ];

        for( int i=0; i<rows; i++ ) {

            for( int j=0; j<cols; j++ ) {

                this.vis[i][j] = false;

            }

        }

    }



    private boolean isValid( int row, int col ) { // whether it can visit this position

        if( row < 0 || row >= this.rows || col < 0 || col >= this.cols || vis[row][col] || this.grids[row][col] == EMPTY ) {

            return false;

        }

        return true;

    }



    public void readGrids( Scanner in ) {

        String str;

        for( int i=0; i<rows; i++ ) {

            this.grids[i] = in.next().toCharArray();

        }

    }



    public void Search( int row, int col ) { // search this grid and its adjacent grids

        if( !this.isValid( row, col ) ) {

            return ;

        }

        this.vis[row][col] = true;

        for( int i=0; i<8; i ++ ) {

            Search( row+dir[i][0], col+dir[i][1] );

        }

    }



    public int getPocketsAmount() {

        int counter = 0;

        for( int i=0; i<this.rows; i++ ) {

            for( int j=0; j<this.cols; j++ ) {

                if( this.grids[i][j] == '@' && !this.vis[i][j] ) {

                    counter ++;

                    this.Search( i, j );

                }

            }

        }

        return counter;

    }

}

 其中之所以将Scanner的对象进行传递，是因为如果重新声明一个Scanner的对象，会使输入出错，错误的具体表现为一直等待输入，尽管已经在Console中输入了数据。猜测可能是未关闭上一个Scanner的对象导致的，所以这里将Scanner的对象进行传递。