poj 3057 Evacuation

占位置。。

  1 /*Author :usedrose  */

  2 /*Created Time :2015/7/27 0:51:12*/

  3 /*File Name :2.cpp*/

  4 #include <cstdio>

  5 #include <iostream>

  6 #include <algorithm>

  7 #include <sstream>

  8 #include <cstdlib>

  9 #include <cstring>

 10 #include <climits>

 11 #include <vector>

 12 #include <string>

 13 #include <ctime>

 14 #include <cmath>

 15 #include <deque>

 16 #include <queue>

 17 #include <stack>

 18 #include <set>

 19 #include <map>

 20 #define INF 0x3f3f3f3f

 21 #define eps 1e-8

 22 #define pi acos(-1.0)

 23 #define MAXN 15

 24 #define MAXM 10010

 25 #define OK cout << "ok" << endl;

 26 #define o(a) cout << #a << " = " << a << endl

 27 #define o1(a,b) cout << #a << " = " << a << "  " << #b << " = " << b << endl

 28 using namespace std;

 29 typedef long long LL;

 30 const int dx[4] = { -1, 0, 0, 1 }, dy[4] = { 0, -1, 1, 0 };

 31 int V;

 32 vector<int> G[MAXM];

 33 int match[MAXM];

 34 bool used[MAXM];

 35 int dist[MAXN][MAXN][MAXN][MAXN];

 36 char field[MAXN][MAXN];

 37 int X, Y;

 38 vector<int> dX, dY, pX, pY;

 39 

 40 void addedge(int u, int v)

 41 {

 42     G[u].push_back(v);

 43     G[v].push_back(u);

 44 }

 45 

 46 bool dfs(int v)

 47 {

 48     used[v] = true;

 49     for (int i = 0; i < G[v].size(); ++i) {

 50         int u = G[v][i], w = match[u];

 51         if (w < 0 || !used[w] && dfs(w)) {

 52             match[v] = u;

 53             match[u] = v;

 54             return true;

 55         }

 56     }

 57     return false;

 58 }

 59 

 60 void bfs(int x, int y, int d[MAXN][MAXN])

 61 {

 62     queue<int> qx, qy;

 63     d[x][y] = 0;

 64     qx.push(x);

 65     qy.push(y);

 66     while (!qx.empty()) {

 67         x = qx.front(); qx.pop();

 68         y = qy.front(); qy.pop();

 69         for (int k = 0; k < 4; ++k) {

 70             int x2 = x + dx[k], y2 = y + dy[k];

 71             if (0 <= x2 && x2 < X && 0 <= y2 && y2 < Y && field[x2][y2] == '.' && d[x2][y2] < 0) {

 72                 d[x2][y2] = d[x][y] + 1;

 73                 qx.push(x2);

 74                 qy.push(y2);

 75             }

 76         }

 77     }

 78 }

 79 

 80 

 81 void solve()

 82 {

 83     int n = X*Y;

 84     dX.clear(); dY.clear();

 85     pX.clear(); pY.clear();

 86     memset(dist, -1, sizeof(dist));

 87     

 88     for (int x = 0; x < X; ++x) {

 89         for (int y = 0; y < Y; ++y) {

 90             if (field[x][y] == 'D') {

 91                 dX.push_back(x);

 92                 dY.push_back(y);

 93                 bfs(x, y, dist[x][y]);

 94             }

 95             else if (field[x][y] == '.') {

 96                 pX.push_back(x);

 97                 pY.push_back(y);

 98             }

 99 

100         }

101     }

102 

103     int d = dX.size(), p = pX.size();

104     for (int i = 0; i < n*d; ++i)

105         G[i].clear();

106     for (int i = 0; i < d; ++i) {

107         for (int j = 0; j < p; ++j) {

108             if (dist[dX[i]][dY[i]][pX[j]][pY[j]] >= 0) {

109                 for (int k = dist[dX[i]][dY[i]][pX[j]][pY[j]]; k <= n; ++k) {

110                     addedge((k - 1)*d + i, n*d + j);

111                 }

112             }

113         }

114     }

115 

116     if (p == 0) {

117         cout << 0 << endl;

118         return;

119     }

120     int num = 0;

121     memset(match, -1, sizeof(match));

122     for (int v = 0; v < n*d; ++v) {

123         memset(used, 0, sizeof(used));

124         if (dfs(v)) {

125             if (++num == p) {

126                 cout << v / d + 1 << endl;

127                 return;

128             }

129         }

130     }

131     cout << "impossible" << endl;

132 }

133 

134 

135 int main()

136 {

137     //freopen("data.in","r",stdin);

138     //freopen("data.out","w",stdout);

139     cin.tie(0);

140     ios::sync_with_stdio(false);

141     int T;

142     cin >> T;

143     while (T--) {

144         cin >> X >> Y;

145         for (int i = 0; i < X; ++i)

146             cin >> field[i];

147         solve();

148     }

149     return 0;

150 }

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