poj 3057 Evacuation

占位置。。

/*Author :usedrose  */
/*Created Time :2015/7/27 0:51:12*/
/*File Name :2.cpp*/
#include <cstdio>
#include <iostream>
#include <algorithm>
#include <sstream>
#include <cstdlib>
#include <cstring>
#include <climits>
#include <vector>
#include <string>
#include <ctime>
#include <cmath>
#include <deque>
#include <queue>
#include <stack>
#include <set>
#include <map>
#define INF 0x3f3f3f3f
#define eps 1e-8
#define pi acos(-1.0)
#define MAXN 15
#define MAXM 10010
#define OK cout << "ok" << endl;
#define o(a) cout << #a << " = " << a << endl
#define o1(a,b) cout << #a << " = " << a << "  " << #b << " = " << b << endl
using namespace std;
typedef long long LL;
const int dx[4] = { -1, 0, 0, 1 }, dy[4] = { 0, -1, 1, 0 };
int V;
vector<int> G[MAXM];
int match[MAXM];
bool used[MAXM];
int dist[MAXN][MAXN][MAXN][MAXN];
char field[MAXN][MAXN];
int X, Y;
vector<int> dX, dY, pX, pY;

void addedge(int u, int v)
{
    G[u].push_back(v);
    G[v].push_back(u);
}

bool dfs(int v)
{
    used[v] = true;
    for (int i = 0; i < G[v].size(); ++i) {
        int u = G[v][i], w = match[u];
        if (w < 0 || !used[w] && dfs(w)) {
            match[v] = u;
            match[u] = v;
            return true;
        }
    }
    return false;
}

void bfs(int x, int y, int d[MAXN][MAXN])
{
    queue<int> qx, qy;
    d[x][y] = 0;
    qx.push(x);
    qy.push(y);
    while (!qx.empty()) {
        x = qx.front(); qx.pop();
        y = qy.front(); qy.pop();
        for (int k = 0; k < 4; ++k) {
            int x2 = x + dx[k], y2 = y + dy[k];
            if (0 <= x2 && x2 < X && 0 <= y2 && y2 < Y && field[x2][y2] == '.' && d[x2][y2] < 0) {
                d[x2][y2] = d[x][y] + 1;
                qx.push(x2);
                qy.push(y2);
            }
        }
    }
}


void solve()
{
    int n = X*Y;
    dX.clear(); dY.clear();
    pX.clear(); pY.clear();
    memset(dist, -1, sizeof(dist));
    
    for (int x = 0; x < X; ++x) {
        for (int y = 0; y < Y; ++y) {
            if (field[x][y] == 'D') {
                dX.push_back(x);
                dY.push_back(y);
                bfs(x, y, dist[x][y]);
            }
            else if (field[x][y] == '.') {
                pX.push_back(x);
                pY.push_back(y);
            }

        }
    }

    int d = dX.size(), p = pX.size();
    for (int i = 0; i < n*d; ++i)
        G[i].clear();
    for (int i = 0; i < d; ++i) {
        for (int j = 0; j < p; ++j) {
            if (dist[dX[i]][dY[i]][pX[j]][pY[j]] >= 0) {
                for (int k = dist[dX[i]][dY[i]][pX[j]][pY[j]]; k <= n; ++k) {
                    addedge((k - 1)*d + i, n*d + j);
                }
            }
        }
    }

    if (p == 0) {
        cout << 0 << endl;
        return;
    }
    int num = 0;
    memset(match, -1, sizeof(match));
    for (int v = 0; v < n*d; ++v) {
        memset(used, 0, sizeof(used));
        if (dfs(v)) {
            if (++num == p) {
                cout << v / d + 1 << endl;
                return;
            }
        }
    }
    cout << "impossible" << endl;
}


int main()
{
    //freopen("data.in","r",stdin);
    //freopen("data.out","w",stdout);
    cin.tie(0);
    ios::sync_with_stdio(false);
    int T;
    cin >> T;
    while (T--) {
        cin >> X >> Y;
        for (int i = 0; i < X; ++i)
            cin >> field[i];
        solve();
    }
    return 0;
}