hdu1241（Oil Deposits）

Problem Description

Input

Output

Sample Input

1 1
*
3 5
*@*@*
**@**
*@*@*
1 8
@@****@*
5 5 
****@
*@@*@
*@**@
@@@*@
@@**@
0 0 

0
1
2
2

import java.util.Scanner;

public class SearchMethodBFS {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		while(sc.hasNext()){
			int m = sc.nextInt();//行
			int n = sc.nextInt();//列
			if(m==0){
				break;
			}
			
			//输入图(初始化)
			Plot plots[][] = new Plot[m][n];
			for(int i=0;i<m;i++){
				String str = sc.next();//如果此处用nextLine()，则前面输入n时的换行符应该先吸掉
				for(int j=0;j<n;j++){
					plots[i][j] = new Plot();
					plots[i][j].x = i;
					plots[i][j].y = j;
					plots[i][j].c = str.charAt(j);
				}
			}
			
			//搜索，查看有几个图块
			int count=0;
			for(int i=0;i<m;i++){
				for(int j=0;j<n;j++){
					if(plots[i][j].c=='@' && !plots[i][j].isVisited){
						//广搜
						PlotQue queue = new PlotQue();
						queue.add(plots[i][j]);
						bfs(plots,queue);
						count++;
					}
				}
			}
			System.out.println(count);
		}
	}

	private static void bfs(Plot[][] plots, PlotQue queue) {
		int px,py;//当前所搜的位置：第px行py列
		int m = plots.length;//地图的行数
		int n = plots[0].length;//地图的列数
		
		while(!queue.isEmpty()){
			Plot plot = queue.pop();
			for(int i=0;i<8;i++){
				px=plot.x+dir[i][0];
				py=plot.y+dir[i][1];
				if(px>=0&&px<m && py>=0&&py<n  &&
				   plots[px][py].c=='@' && !plots[px][py].isVisited){
					plots[px][py].isVisited = true;
					queue.add(plots[px][py]);
				}
			}
		}
	}
	
	final static int dir[][]={
		{0,-1}, //上
		{0,1}, //下
		{-1,0}, //左
		{1,0}, //右
		{-1,-1}, //左上
		{1,-1}, //右上
		{-1,1}, //左下
		{1,1}, //右下
	};
}

class Plot{
	int x,y;//位置:第x行y列
	char c;
	boolean isVisited=false;
}

class PlotQue{
	Plot plots[];
	final int FRONT =0;
	int end;
	public PlotQue(){
		plots = new Plot[100];
		end = 0;
	}
	public void add(Plot p){
		plots[end] = p;
		end++;
	}
	public Plot pop(){
		if(end<=0){
			return null;
		}
		Plot p = plots[FRONT];
		//出队列：把队首的元素从队列中移出
		if(end>1){
			for(int i=0;i<end;i++){
				plots[i] = plots[i+1];
			}
		}
		end--;		
		return p;
	}
	public boolean isEmpty(){
		if(end<=0){
			return true;
		}
		return false;
	}
}

优化：循环队列

import java.util.Scanner;

public class SearchMethodBFS {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		while(sc.hasNext()){
			int m = sc.nextInt();//行
			int n = sc.nextInt();//列
			if(m==0){
				break;
			}
			
			//输入图(初始化)
			PPlot plots[][] = new PPlot[m][n];
			for(int i=0;i<m;i++){
				String str = sc.next();//如果此处用nextLine()，则前面输入n时的换行符应该先吸掉
				for(int j=0;j<n;j++){
					plots[i][j] = new PPlot();
					plots[i][j].x = i;
					plots[i][j].y = j;
					plots[i][j].c = str.charAt(j);
				}
			}
			
			//搜索，查看有几个图块
			int count=0;
			for(int i=0;i<m;i++){
				for(int j=0;j<n;j++){
					if(plots[i][j].c=='@' && !plots[i][j].isVisited){
						//广搜
						
						CirclingQueue queue = new CirclingQueue();
						queue.add(plots[i][j]);
						bfs(plots,queue);
						count++;
					}
				}
			}
			System.out.println(count);
		}
	}

	private static void bfs(PPlot[][] plots, CirclingQueue queue) {
		int px,py;//当前所搜的位置：第px行py列
		int m = plots.length;//地图的行数
		int n = plots[0].length;//地图的列数
		
		while(!queue.isEmpty()){
			PPlot plot = queue.pop();
			for(int i=0;i<8;i++){
				px=plot.x+dir[i][0];
				py=plot.y+dir[i][1];
				//※px代表的是行号，行号的边界要用m来界定。py同理
				if(px>=0&&px<m && py>=0&&py<n  &&
				   plots[px][py].c=='@' && !plots[px][py].isVisited){
					plots[px][py].isVisited = true;
					queue.add(plots[px][py]);
				}
			}
		}
	}
	
	final static int dir[][]={
		{0,-1}, //上
		{0,1}, //下
		{-1,0}, //左
		{1,0}, //右
		{-1,-1}, //左上
		{1,-1}, //右上
		{-1,1}, //左下
		{1,1}, //右下
	};
}

class PPlot{
	int x,y;//位置:第x行y列
	char c;
	boolean isVisited=false;
	public PPlot(int x, int y) {
		this.x = x;
		this.y = y;
	}
	public PPlot() {
	}
	@Override
	public String toString() {
		return "PPlot [x=" + x + ", y=" + y + ", c=" + c + ", isVisited="
				+ isVisited + "]";
	}
	
}

class CirclingQueue{
	PPlot plots[];
	int front;
	int end;
	private final int MAX_SIZE=5;
		
	public CirclingQueue(){
		plots = new PPlot[MAX_SIZE];
		front =0;
		end = 0;
	}
	
	public void add(PPlot p){
		if(isFull()){
			System.out.println("Adding failure,the queue is Full!!!");
		}else{
			plots[end] = p;
			end = (end+1)%MAX_SIZE;
		}
	}
	private boolean isFull() {
		if((end+1)%MAX_SIZE==front){
			return true;
		}else{
		  return false;
		}
	}
	public boolean isEmpty(){
		return front==end ? true : false;
	}
	
	public PPlot pop(){
		if(isEmpty()){
			System.out.println("Poping failure,the queue is Empty!!!");
			return null;
		}
		
		PPlot p = plots[front];
		front = (front+1)%MAX_SIZE;
		return p;
	}
}

深搜也可以：http://blog.csdn.net/u011479875/article/details/47210941

hdu1241（Oil Deposits）

原文：http://blog.csdn.net/u011479875/article/details/47282747