BZOJ 1266 [AHOI2006]上学路线route

  1 #include <queue>
  2 #include <vector>
  3 #include <cstdio>
  4 #include <cstring>
  5 #include <algorithm>
  6 
  7 using namespace std;
  8 
  9 const size_t Max_N(505);
 10 const size_t Max_M(600050);
 11 const int INF(0X7F7F7F7F);
 12 
 13 void Get_Val(unsigned int &ret)
 14 {
 15     ret = 0;
 16     char ch;
 17     while ((ch = getchar()), (ch > ‘9‘ || ch < ‘0‘))
 18         ;
 19     do
 20     {
 21         (ret *= 10) += ch - ‘0‘;
 22     }
 23     while ((ch = getchar()), (ch >= ‘0‘ && ch <= ‘9‘));
 24 }
 25 
 26 void Get_Val(int &ret)
 27 {
 28     ret = 0;
 29     char ch;
 30     while ((ch = getchar()), (ch > ‘9‘ || ch < ‘0‘))
 31         ;
 32     do
 33     {
 34         (ret *= 10) += ch - ‘0‘;
 35     }
 36     while ((ch = getchar()), (ch >= ‘0‘ && ch <= ‘9‘));
 37 }
 38 
 39 struct edge
 40 {
 41     edge(const size_t &a = 0, const int &b = 0, const int &c = 0) : To(a), Time(b), Cost(c) {}
 42     size_t To;
 43     int Time, Cost;
 44 };
 45 
 46 size_t N;
 47 int G[Max_N][Max_N];
 48 vector<edge> Adj[Max_N];
 49 
 50 unsigned int Total;
 51 unsigned int Head[Max_N];
 52 unsigned int To[Max_M], Next[Max_M];
 53 int Cap[Max_M], Flow[Max_M];
 54 
 55 inline
 56 void Add_Edge(const size_t &tot, const size_t &s, const size_t &t, const int &c)
 57 {
 58     To[tot] = t;
 59     Next[tot] = Head[s], Head[s] = tot;
 60     Cap[tot] = c, Flow[tot] = 0;
 61 }
 62 
 63 void init()
 64 {
 65     unsigned int M;
 66     size_t u, v;
 67     int t, c;
 68     Get_Val(N);
 69     Get_Val(M);
 70     memset(G, 0X3F, sizeof(G));
 71     for (size_t i = 1;i <= N;++i)
 72         G[i][i] = 0;
 73     while (M--)
 74     {
 75         Get_Val(u);
 76         Get_Val(v);
 77         Get_Val(t);
 78         Get_Val(c);
 79         G[u][v] = G[v][u] = t;
 80         Adj[u].push_back(edge(v, t, c));
 81         Adj[v].push_back(edge(u, t, c));
 82     }
 83 }
 84 
 85 void Floyd()
 86 {
 87     for (size_t k = 1;k <= N;++k)
 88         for (size_t i = 1;i <= N;++i)
 89             for (size_t j = 1;j <= N;++j)
 90                 G[i][j] = min(G[i][j], G[i][k] + G[k][j]);
 91     for (size_t u = 1;u <= N;++u)
 92         for (size_t i = 0;i != Adj[u].size();++i)
 93             if (G[1][u] + Adj[u][i].Time + G[Adj[u][i].To][N] == G[1][N])
 94             {
 95                 Total += 2;
 96                 Add_Edge(Total, u, Adj[u][i].To, Adj[u][i].Cost);
 97                 Add_Edge(Total ^ 1, Adj[u][i].To, u, 0);
 98             }
 99             
100 }
101 
102 unsigned int Dist[Max_N];
103 size_t Cur[Max_N];
104 bool BFS(const size_t &S, const size_t &T)
105 {
106     memset(Dist, 0, sizeof(Dist));
107     queue<size_t> Q;
108     Q.push(S);
109     Dist[S] = 1;
110     size_t Top;
111     
112     while (Q.size())
113     {
114         Top = Q.front();
115         Q.pop();
116         for (size_t i = Head[Top];i;i = Next[i])
117             if (!Dist[To[i]] && Cap[i] > Flow[i])
118             {
119                 Dist[To[i]] = Dist[Top] + 1;
120                 Q.push(To[i]);
121             }
122     }
123     
124     return Dist[T];
125 }
126 
127 int DFS(const size_t &u, int a, const size_t &T)
128 {
129     if (u == T || a == 0)
130         return a;
131     int Ans(0), f;
132     for (size_t &i = Cur[u];i;i = Next[i])
133         if (Dist[To[i]] == Dist[u] + 1)
134             if (((f = DFS(To[i], min(a, Cap[i] - Flow[i]), T))) > 0)
135             {
136                 Ans += f;
137                 a -= f;
138                 Flow[i] += f;
139                 Flow[i ^ 1] -= f;
140                 if (a == 0)
141                     break;
142             }
143     return Ans;
144 }
145 
146 int Dinic(const size_t &S, const size_t &T)
147 {
148     int Ans(0);
149     while (BFS(S, T))
150     {
151         for (size_t i = 1;i <= N;++i)
152             Cur[i] = Head[i];
153         Ans += DFS(S, INF, T);
154     }
155     return Ans;
156 }
157 
158 int main()
159 {
160     init();
161     
162     Floyd();
163     
164     printf("%d\n%d", G[1][N], Dinic(1, N));
165     
166     return 0;
167 }