卜若的代碼筆記-數據結構系列-第十八章：隊列的經典應用.廣度搜索

1.先來看題目

實現原理很簡單，就是從邊緣向內部搜索，你可以深度搜索或者廣度搜索。就不做介紹了

/*
 * @lc app=leetcode.cn id=130 lang=java
 *
 * [130] 被圍繞的區域
 */

// @lc code=start
class Solution {
    
    public void solve(char[][] board) {
        
        bfs(board);
    }

public static void bfs(char[][] data){
        int h = data.length;

        if (h == 0)
            return;
        int w = data[0].length;
        Character[][] d2 = new Character[h][w];
        int[][] flag = new int[h][w];
        for (int i =0;i<h;i++){

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

                d2[i][j] = data[i][j];
                flag[i][j] = 0;
            }
        }

        Queue<IPoint> points = new LinkedList<>();
        for (int i =0;i<h;i++){
            for (int j =0;j<w;j++){
                if (d2[i][j].toString() .equals("O") ){

                    if (i == 0||i == h-1||j == 0||j== w-1){

                        points.offer(new CPoint(i,j,d2));

                    }

                }

            }
        }
        //Debug.Log(points.size());

        while (points.size()!= 0){

            IPoint c1 = points.poll();
            //.Log(c1.getValue().toString());
            List<IPoint> nextList = c1.nextPoint(c1,d2);
            flag[c1.getX()][c1.getY()] = 100;
            //Debug.Log(c1.getX()+"<>"+c1.getY());
            for (IPoint p : nextList){


                if (p.isLegal(p.getX(),p.getY(),d2)){

                    if (p.getValue().toString().equals("O")){
                        if (flag[p.getX()][p.getY()]  != 100){

                            points.offer(p);
                        }

                    }

                }
            }



        }


        String value = "";
        for (int i =0;i<h;i++){

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

                if (flag[i][j] !=100){
                    data[i][j] = 'X';
                }
                value+= data[i][j];
            }
            value+= "\n";
        }

        //Debug.Log(value);
    }
}

interface IPoint <T> {

    boolean isLegal(int x,int y,T[][] arr);
    List<IPoint> nextPoint(IPoint point,T[][] arr);
    int getX();
    int getY();
    T getValue();
    IPoint getParent();
    IPoint setParent(IPoint parent);
    IPoint getChild();
    IPoint setChild(IPoint child);
}
class CPoint<T> implements IPoint<T> {

    T value;
    int x;
    int y;
    IPoint<T> child;
    IPoint<T> parent;
    public CPoint(int x,int y,T[][] arr){

        this.x = x;
        this.y = y;
        this.value = arr[x][y];

    }
    @Override
    public boolean isLegal(int x, int y, T[][] arr) {


        int w = arr.length;
        int h = arr[0].length;
        if(x <= 0)
        {
            return false;
        }
        if(y<= 0){

            return false;
        }

        if(x> w-1){
            return false;
        }
        if(y > h-1){

            return false;
        }
        return true;
    }

    @Override
    public List<IPoint> nextPoint(IPoint point,T[][] arr) {

        List<IPoint> pl = new ArrayList();

        int[][] dir = new int[4][2];
        dir[0] = new int[]{point.getX() - 1,point.getY()};
        dir[1] = new int[]{point.getX()+ 1,point.getY()};
        dir[2] = new int[]{point.getX(),point.getY() +1};
        dir[3] = new int[]{point.getX(),point.getY() -1};

        for (int i =0;i<4;i++){
            if(isLegal(dir[i][0],dir[i][1],arr)){
                CPoint c1 = new CPoint(dir[i][0],dir[i][1],arr);

                c1.setParent(this);

                pl.add(c1);
            }
        }
        return pl;
    }

    @Override
    public int getX() {
        return x;
    }

    @Override
    public int getY() {
        return y;
    }

    @Override
    public T getValue() {
        return value;
    }

    @Override
    public IPoint getParent() {


        return parent;
    }

    @Override
    public IPoint setParent(IPoint parent) {
        this.parent = parent;
        return parent;
    }

    @Override
    public IPoint getChild() {
        return child;
    }

    @Override
    public IPoint setChild(IPoint child) {
        this.child = child;
        return parent;
    }
}





// @lc code=end