Fire! UVA11624


#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <queue>
#include <algorithm>
#include <vector>
#include <cstring>
#include <stack>
#include <cctype>
#include <utility>   
#include <map>
#include <string>  
#include <climits> 
#include <set>
#include <string>    
#include <sstream>
#include <utility>   
#include <ctime>

using std::priority_queue;
using std::vector;
using std::swap;
using std::stack;
using std::sort;
using std::max;
using std::min;
using std::pair;
using std::map;
using std::string;
using std::cin;
using std::cout;
using std::set;
using std::queue;
using std::string;
using std::istringstream;
using std::make_pair;
using std::greater;
using std::endl;

const int MAXN(1010);
const int MAXM(1000010);

int fire[MAXN][MAXN];
char mp[MAXN][MAXN];
bool vis[MAXN][MAXN];
int fx[MAXM], fy[MAXM];
int R, C, SX, SY;

struct NODE
{
	int x, y, dist;
	NODE()
	{}
	NODE(int tx, int ty, int td): x(tx), y(ty), dist(td)
	{}
};

int move_x[4] = {0, -1, 0, 1};
int move_y[4] = {-1, 0, 1, 0};

void bfs1(int n)
{
	queue<NODE> que;
	memset(fire+1, -1, sizeof(fire[0])*R);
	for(int i = 0; i < n; ++i)
	{
		que.push(NODE(fx[i], fy[i], 0));
		fire[fx[i]][fy[i]] = 0;
	}
	NODE cur;
	while(!que.empty())
	{
		cur = que.front();
		que.pop();
		for(int i = 0; i < 4; ++i)
		{
			int nx = cur.x+move_x[i], ny = cur.y+move_y[i];
			if(nx >= 1 && nx <= R && ny >= 1 && ny <= C && mp[nx][ny] != '#' && fire[nx][ny] == -1)
			{
				fire[nx][ny] = cur.dist+1;
				que.push(NODE(nx, ny, cur.dist+1));	
			}
		}
	}
}

int bfs2(void)
{
	queue<NODE> que;
	memset(vis+1, 0, sizeof(vis[0])*R);
	que.push(NODE(SX, SY, 0));
	vis[SX][SY] = true;
	NODE cur;
	while(!que.empty())
	{
		cur = que.front();
		que.pop();
		if(cur.x == 1 || cur.y == 1 || cur.x == R || cur.y == C)
			return cur.dist+1;
		for(int i = 0; i < 4; ++i)
		{
			int nx = cur.x+move_x[i], ny = cur.y+move_y[i];
			if(nx >= 1 && nx <= R && ny >= 1 && ny <= C && mp[nx][ny] != '#' && !vis[nx][ny] && (fire[nx][ny] == -1 || cur.dist+1 < fire[nx][ny]))
			{
				vis[nx][ny] = true;
				que.push(NODE(nx, ny, cur.dist+1));
			}
		}
	}
	return -1;
}

int main()
{
	int T;
	scanf("%d", &T);
	while(T--)
	{
		scanf("%d%d", &R, &C);
		int count = 0;
		for(int i = 1; i <= R; ++i)
		{
			scanf("%s", mp[i]+1);
			for(int j = 1; j <= C; ++j)
			{
				if(mp[i][j] == 'J')
				{
					SX = i;
					SY = j;
				}
				if(mp[i][j] == 'F')
				{
					fx[count] = i;
					fy[count++] = j;
				}
			}
		}
		bfs1(count);
		int ans = bfs2();
		if(ans == -1)
			printf("IMPOSSIBLE\n");
		else
			printf("%d\n", ans);
	}
	return 0;
}


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