题目传送门
1 /*
2 BFS：首先对火搜索，求出火蔓延到某点的时间，再对J搜索，如果走到的地方火已经烧到了就不入队，直到走出边界。
3 */
4 /************************************************
5 Author :Running_Time
6 Created Time :2015-8-4 8:11:54
7 File Name :UVA_11624.cpp
8 *************************************************/
9
10 #include <cstdio>
11 #include <algorithm>
12 #include <iostream>
13 #include <sstream>
14 #include <cstring>
15 #include <cmath>
16 #include <string>
17 #include <vector>
18 #include <queue>
19 #include <deque>
20 #include <stack>
21 #include <list>
22 #include <map>
23 #include <set>
24 #include <bitset>
25 #include <cstdlib>
26 #include <ctime>
27 using namespace std;
28
29 #define lson l, mid, rt << 1
30 #define rson mid + 1, r, rt << 1 | 1
31 typedef long long ll;
32 const int MAXN = 1e3 + 10;
33 const int INF = 0x3f3f3f3f;
34 const int MOD = 1e9 + 7;
35 char maze[MAXN][MAXN];
36 bool vis[MAXN][MAXN];
37 int step[MAXN][MAXN];
38 int dx[4] = {-1, 1, 0, 0};
39 int dy[4] = {0, 0, -1, 1};
40 int n, m;
41
42 bool judge_f(int x, int y) {
43 if (x < 1 || x > n || y < 1 || y > m || vis[x][y] || maze[x][y] == '#') return false;
44 return true;
45 }
46
47 bool judge_j(int x, int y) {
48 if (x < 1 || x > n || y < 1 || y > m) return true;
49 return false;
50 }
51
52 void BFS_F(void) {
53 memset (step, INF, sizeof (step));
54 memset (vis, false, sizeof (vis));
55 queue<pair<int, int> > Q;
56 for (int i=1; i<=n; ++i) {
57 for (int j=1; j<=m; ++j) {
58 if (maze[i][j] == 'F') {
59 Q.push (make_pair (i, j)); vis[i][j] = true;
60 step[i][j] = 0;
61 }
62 }
63 }
64 while (!Q.empty ()) {
65 int x = Q.front ().first, y = Q.front ().second; Q.pop ();
66 for (int i=0; i<4; ++i) {
67 int tx = x + dx[i], ty = y + dy[i];
68 if (!judge_f (tx, ty)) continue;
69 step[tx][ty] = step[x][y] + 1;
70 Q.push (make_pair (tx, ty)); vis[tx][ty] = true;
71 }
72 }
73 }
74
75 void BFS_J(void) {
76 memset (vis, false, sizeof (vis));
77 queue<pair<int, int> > Q;
78 for (int i=1; i<=n; ++i) {
79 for (int j=1; j<=m; ++j) {
80 if (maze[i][j] == 'J') {
81 Q.push (make_pair (i, j)); step[i][j] = 0; vis[i][j] = true; break;
82 }
83 }
84 }
85 while (!Q.empty ()) {
86 int x = Q.front ().first, y = Q.front ().second; Q.pop ();
87 for (int i=0; i<4; ++i) {
88 int tx = x + dx[i], ty = y + dy[i];
89 if (judge_j (tx, ty)) {
90 printf ("%d
", step[x][y] + 1); return ;
91 }
92 if (step[x][y] + 1 >= step[tx][ty] || vis[tx][ty] || maze[tx][ty] == '#') continue;
93 Q.push (make_pair (tx, ty)); step[tx][ty] = step[x][y] + 1; vis[tx][ty] = true;
94 }
95 }
96 puts ("IMPOSSIBLE");
97 }
98
99 int main(void) { //UVA 11624 Fire!
100 int T; scanf ("%d", &T);
101 while (T--) {
102 scanf ("%d%d", &n, &m);
103 for (int i=1; i<=n; ++i) {
104 scanf ("%s", maze[i] + 1);
105 }
106 BFS_F (); BFS_J ();
107 }
108
109 return 0;
110 }