[ACM] UVa 11624 Fire!

#include<iostream>#include<queue>#include<cstring>using namespace std;const int MAXDATA = 1005;const int NOTV = -1;const int OPR[4][2] = { 0, 1, 0, -1, 1, 0, -1, 0};struct d2Pos {    int x, y, d;};int X__, Y__, R__;char g[MAXDATA][MAXDATA];int fire[MAXDATA][MAXDATA],    joev[MAXDATA][MAXDATA];queue<d2Pos> fireQ;d2Pos joe;void readg() {    R__ = 0;    while (!fireQ.empty())        fireQ.pop();    cin >> X__ >> Y__;    for (int i = 0; i < X__; i++) {        for (int j = 0; j < Y__; j++) {            char t;            cin >> t;            g[i][j] = t;            joev[i][j] = NOTV;            switch (t) {            case 'J':                joev[i][j] = 0;                fire[i][j] = NOTV;                joe.x = i; joe.y = j; joe.d = 0;            case '.':                fire[i][j] = NOTV;                break;            case 'F':                fire[i][j] = 0;                d2Pos t1;                t1.x = i; t1.y = j; t1.d = 0;                fireQ.push(t1);            }        }    }}bool inmaze(d2Pos t) {    return (t.x >= 0 && t.y >= 0 && t.x < X__ && t.y < Y__);}void Search_Fire() {    d2Pos t, v;    while (!fireQ.empty()) {        t = fireQ.front();        fireQ.pop();        for (int i = 0; i < 4; i++) {            v.d = t.d + 1;            v.x = t.x + OPR[i][0];            v.y = t.y + OPR[i][1];            if (!inmaze(v))                continue;            if (g[v.x][v.y] == '#')                continue;            if (fire[v.x][v.y] != NOTV)                continue;            fireQ.push(v);            fire[v.x][v.y] = v.d;        }    }}void Search_Joe() {    queue<d2Pos> Q;    Q.push(joe);    d2Pos t, v;    while (!Q.empty()) {        t = Q.front();        Q.pop();        if (t.x == 0 || t.y == 0 || t.x == X__ - 1 || t.y == Y__ - 1) {            R__ = t.d + 1;            return;        }        for (int i = 0; i < 4; i++) {            v.d = t.d + 1;            v.x = t.x + OPR[i][0];            v.y = t.y + OPR[i][1];            if (!inmaze(v))                continue;            if (g[v.x][v.y] == '#')                continue;            if (fire[v.x][v.y] != NOTV && v.d >= fire[v.x][v.y])                continue;            if (joev[v.x][v.y] != -1)                continue;            Q.push(v);            joev[v.x][v.y] = v.d;        }    }}int main() {    int T;    cin >> T;    while (T--) {        readg();        Search_Fire();        Search_Joe();        if (R__ == 0)            cout << "IMPOSSIBLE" << endl;        else            cout << R__ << endl;    }    return 0;}