bzoj-1834 network 网络扩容 【网络流】

　　这题就是复习下网络流。

 #include <bits/stdc++.h>
 #define rep(i, a, b) for (int i = a; i <= b; i++)
 #define drep(i, a, b) for (int i = a; i >= b; i--)
 #define REP(i, a, b) for (int i = a; i < b; i++)
 #define mp make_pair
 #define pb push_back
 #define clr(x) memset(x, 0, sizeof(x))
 #define xx first
 #define yy second
 using namespace std;
 typedef long long i64;
 typedef pair<int, int> pii;
 const int inf = ~0U >> ;
 const i64 INF = ~0ULL >> ;
 //********************************

 const int maxn = , maxm = ;

 struct Ed {
     int u, v, nx, c, w; Ed() {}
     Ed(int _u, int _v, int _nx, int _c, int _w) :
         u(_u), v(_v), nx(_nx), c(_c), w(_w) {}
 } E[maxm << ];
 int G[maxn], edtot, cur[maxn];
 void addedge(int u, int v, int c, int w) {
     E[edtot] = Ed(u, v, G[u], c, w);
     G[u] = edtot++;
     E[edtot] = Ed(v, u, G[v], , -w);
     G[v] = edtot++;
 }

 int level[maxn], s , t;
 bool bfs() {
     static int que[maxn]; int qh(), qt();
     clr(level);
     level[que[++qt] = s] = ;
     while (qh != qt) {
         int x = que[++qh];
         for (int i = G[x]; i != -; i = E[i].nx) if (!level[E[i].v] && E[i].c) {
             level[que[++qt] = E[i].v] = level[x] + ;
         }
     }
     return !!level[t];
 }
 int dfs(int u, int rm) {
     if (u == t) return rm;
     int rm1 = rm;
     for (int &i = cur[u]; i != -; i = E[i].nx) {
         if (level[E[i].v] == level[u] +  && E[i].c) {
             int flow = dfs(E[i].v, min(rm, E[i].c));
             E[i].c -= flow, E[i ^ ].c += flow;
             if ((rm -= flow) == ) break;
         }
     }
     if (rm1 == rm) level[u] = ;
     return rm1 - rm;
 }

 int dis[maxn], vis[maxn];
 bool spfa() {
     static int que[maxn]; int qh(), qt();
     memset(dis, 0x3f, sizeof(dis));
     clr(vis);
     dis[que[++qt] = s] = , vis[s] = ;
     while (qh != qt) {
         int x = que[++qh]; vis[x] = ;
         for (int i = G[x]; i != -; i = E[i].nx) {
             if (E[i].c && dis[E[i].v] > dis[x] + E[i].w) {
                 dis[E[i].v] = dis[x] + E[i].w;
                 if (!vis[E[i].v]) que[++qt] = E[i].v, vis[E[i].v] = ;
             }
         }
     }
     return dis[t] != 0x3f3f3f3f;
 }
 int ret;
 int dinic(int u, int rm) {
     vis[u] = ;
     if (u == t) return rm;
     int rm1 = rm;
     for (int i = G[u]; i != -; i = E[i].nx) {
         if (dis[E[i].v] == dis[u] + E[i].w && E[i].c && !vis[E[i].v]) {
             int flow = dinic(E[i].v, min(rm , E[i].c));
             E[i].c -= flow, E[i ^ ].c += flow;
             ret += flow * E[i].w;
             if ((rm -= flow) == ) break;
         }
     }
     if (rm1 == rm) dis[u] = ;
     return rm1 - rm;
 }

 int main() {
     int n, m, K;
     scanf("%d%d%d", &n, &m, &K);
     memset(G, -, sizeof(G));
     rep(i, , m) {
         int x, y, c, w;
         scanf("%d%d%d%d", &x, &y, &c, &w);
         addedge(x, y, c, w);
         addedge(x, y, c, );
     }
     s = , t = n + ; addedge(s, , 0x3f3f3f3f, ), addedge(n, t, 0x3f3f3f3f, );
     int ans();
     while (bfs()) memcpy(cur, G, sizeof(G)), ans += dfs(s, 0x3f3f3f3f);
     printf("%d ", ans >> );
     for (int i = ; i <= edtot; i += ) {
         if (E[i].w == ) E[i].c += E[i ^ ].c, E[i ^ ].c = ;
         else E[i].c = 0x3f3f3f3f, E[i ^ ].c = ;
         if (E[i].u == s) E[i].c = (ans >> ) + K;
     }
     while (spfa()) clr(vis), dinic(s, 0x3f3f3f3f);
     printf("%d\n", ret);
 }