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| #include <bits/stdc++.h>
using namespace std;
const int N = 1005;
int x[] = {0, 0, -1, 1};
int y[] = { -1, 1, 0, 0};
int v[N][N], n, m, ans, le, ri;
pair<int, int> q[N * N];
char g[N][N];
void bfs()
{
int cr, cc, r, c;
while(le < ri)
{
cr = q[le].first, cc = q[le++].second;
for(int i = 0; i < 4; ++i)
{
r = cr + x[i], c = cc + y[i];
if(r < 0 || r >= n || c < 0 || c >= m)
ans = ans ? ans : v[cr][cc];
else if(g[r][c] == '.' && (!v[r][c] || v[cr][cc] + 1 < v[r][c]))
v[r][c] = v[cr][cc] + 1, q[ri++] = make_pair(r, c);
}
}
}
int main()
{
int cas, jr, jc;
scanf("%d", &cas);
while(cas--)
{
scanf("%d%d", &n, &m);
for(int i = 0; i < n; ++i)
scanf("%s", g[i]);
memset(v, 0, sizeof(v));
le = ri = 0;
for(int i = 0; i < n; ++i)
for(int j = 0; j < m; ++j)
if(g[i][j] == 'F')
q[ri++] = make_pair(i, j), v[i][j] = 1;
else if(g[i][j] == 'J') jr = i, jc = j;
bfs();
le = ri = ans = 0, v[jr][jc] = 1;
q[ri++] = make_pair(jr, jc);
bfs();
if(ans) printf("%d\n", ans);
else puts("IMPOSSIBLE");
}
return 0;
}
|