杭电1010题

#include<iostream>
#include<vector>
using namespace std;

class Point
{
public:
	int x;
	int y;
	Point():x(0),y(0)
	{
	}
	Point(int a, int b):x(a),y(b)
	{
	}
};

/*
	-1 sink block
	0 empty block
	1 start point 
	2 block of wall
	3 door
	
	for vecMap[x][y]
	move x -- up or down
	move y -- left or right
*/

bool FindWay(Point pStart, vector< vector<int> > vecMap, vector<Point> vecRount,
		 int iTime, Point pDoor)
{
	//从pStart出发，上下左右开始走，加入vecRount
	if(pStart.x == pDoor.x && pStart.y == pDoor.y)
	{
		if(iTime == vecRount.size())
		{
			cout << "TRUE" << endl;
			return true;
		}
		return false;
	}
	
	if(iTime == vecRount.size() )
	{
		/*
		if(3 == vecMap[pStart.x][pStart.y])
		{
			cout << "TRUE" << endl;
			return true;
		}
		cout << "WRONG" << endl;
		for(int i = 0 ; i < vecRount.size(); i++)
		{	
			cout << vecRount[i].x <<"-" << vecRount[i].y << "  "; 
		}
		cout << endl;
		*/
		return false;
	}
	
	bool boFindWay = false;
	
	/*
	find way
		-get new start
		-get new rount
		-find 
	
	*/
		
	if( (0 <= pStart.x - 1) 
		&& (0 == vecMap[pStart.x - 1][pStart.y] || 3 == vecMap[pStart.x - 1][pStart.y]))  // to up
	{
		//cout << " up " << endl;
		Point pNext(pStart.x - 1, pStart.y);
		vector<Point> vecNextRount(vecRount);
		vecNextRount.push_back(pNext);
		//cout << pNext.x  << " ___ "<< pNext.y << endl;
		vecMap[pNext.x][pNext.y] = -1;
		boFindWay = FindWay(pNext, vecMap, vecNextRount, iTime, pDoor);
		
		if(boFindWay == true)
		{
			return boFindWay;
		}
	} //up_loop
	
	if((vecMap.size() > pStart.x + 1 )
		&& (0 == vecMap[pStart.x + 1][pStart.y] || 3 == vecMap[pStart.x + 1][pStart.y]))    // to down
	{
		//cout << " down " << endl;
		Point pNext(pStart.x + 1, pStart.y);
		vector<Point> vecNextRount(vecRount);
		vecNextRount.push_back(pNext);
		//cout << pNext.x  << " ___ "<< pNext.y << endl;
		vecMap[pNext.x][pNext.y] = -1;
		boFindWay = FindWay(pNext, vecMap, vecNextRount, iTime, pDoor);

		if(boFindWay == true)
		{
			return boFindWay;
		}	
	} //down_loop
	
	if( (0 <= pStart.y - 1 )
		&& (0 == vecMap[pStart.x][pStart.y - 1] || 3 == vecMap[pStart.x][pStart.y - 1]))    // to left
	{
		//cout << " left " << endl;
		Point pNext(pStart.x, pStart.y - 1);
		vector<Point> vecNextRount(vecRount);
		vecNextRount.push_back(pNext);
		//cout << pNext.x  << " ___ "<< pNext.y << endl;
		vecMap[pNext.x][pNext.y] = -1;
		boFindWay = FindWay(pNext, vecMap, vecNextRount, iTime, pDoor);
		
		if(boFindWay == true)
		{
			return boFindWay;
		}	
	} //left_loop
	
	if( (vecMap[0].size() > pStart.y + 1)
		&& (0 == vecMap[pStart.x][pStart.y + 1] || 3 == vecMap[pStart.x][pStart.y + 1]))    // to right
	{
		//cout << " right " << endl;
		Point pNext(pStart.x, pStart.y + 1);
		vector<Point> vecNextRount(vecRount);
	  vecNextRount.push_back(pNext);
		//cout << pNext.x  << " ___ "<< pNext.y << endl;
		vecMap[pNext.x][pNext.y] = -1;
		boFindWay = FindWay(pNext, vecMap, vecNextRount, iTime, pDoor);
		
		if(boFindWay == true)
		{
			return boFindWay;
		}	
	} //right_loop
	
	/*
	for(int i = 0 ; i < vecRount.size(); i++)
	{	
		cout << vecRount[i].x <<"-" << vecRount[i].y << "  "; 
	}
	cout << endl;
	*/
	
	return false;
}


int main()
{
	int iLine, iRow;
	int iTime;
	while(cin >> iLine >> iRow >> iTime)
	{
		if(0 == iLine && 0 == iRow && 0 == iTime)
		{
			return 0;
		}
		else
		{
			char ch;
			vector< vector<int> > vecMap(iLine);
			for(int i = 0; i < iLine; i++)
			{	
				vector<int> vecRow(iRow);
				vecMap[i] = vecRow;
			}
			 
			Point pStart, pDoor;
			
			for(int i = 0; i < iLine; i++)
			{
				for(int j = 0; j < iRow; j++)
				{
					cin >> ch;
					if('S' == ch)
					{
						vecMap[i][j] = 1;
						pStart.x = i;
						pStart.y = j;
					}
					else if('.' == ch)
					{
						vecMap[i][j] = 0;
					}
					else if('X' == ch)
					{
						vecMap[i][j] = 2;
					}
					else if('D' == ch)
					{
						vecMap[i][j] = 3;
						pDoor.x = i;
						pDoor.y = j;
					}
				}//for_loop
			}//for_loop
			
			for(int i = 0; i < iLine; i++)
		 	{
				for(int j = 0; j < iRow; j++)
				{
					cout << vecMap[i][j] << " ";
				}//for_loop
				cout << endl;
			}//for_loop
			
			vector<Point> vecRount;
			if(FindWay(pStart, vecMap, vecRount,iTime , pDoor) )
			{
				cout << "YES" << endl;
			}
			else
			{
				cout << "NO" << endl;
			}		
		
		}//if_loop
	
	}//while_loop
	
	return 0;
}

题目：点击打开链接

基本做法：让它随意游走，到时间在看是否走到门口，走到死胡同就回溯。不过，这样笨方法超时了。

参考答案：点击打开链接   （高手写的简单明了，技不如人啊）