BZOJ 1877: [SDOI2009]晨跑

二次联通门 : BZOJ 1877: [SDOI2009]晨跑

 

 

 

 

 

/*
    BZOJ 1877: [SDOI2009]晨跑

    拆点 + 费用流

*/
#include <cstdio>
#include <iostream>
#define rg register
inline void read (int &n) {
    rg char c = getchar ();
    for (n = 0; !isdigit (c); c = getchar ());
    for (; isdigit (c); n = n * 10 + c - '0', c = getchar ());
}
int S, T;
#define Max 7000
#define INF 1e9
namespace net {
    const int MaxE = 2000000;
    int _n[MaxE], _v[MaxE], list[Max], _f[MaxE], _c[MaxE], EC = 1, d[Max], q[MaxE], pre[Max];
    bool is[Max]; int c[Max];
    inline void In (int u, int v, int f, int c) { 
        _v[++ EC] = v, _n[EC] = list[u], list[u] = EC, _f[EC] = f, _c[EC] = c;
        _v[++ EC] = u, _n[EC] = list[v], list[v] = EC, _f[EC] = 0, _c[EC] = -c;
    }

    bool Bfs () { 
        int h = 1, t = 1; q[t] = S; rg int i, n;
        for (i = 0; i <= T; ++ i) d[i] = INF, is[i] = false;
        for (d[S] = 0, c[S] = INF, pre[S] = 0; h <= t; ++ h)
            for (n = q[h], is[n] = false, i = list[n]; i; i = _n[i]) 
                if (d[_v[i]] > d[n] + _c[i] && _f[i]) {
                    d[_v[i]] = d[n] + _c[i], pre[_v[i]] = i, c[_v[i]] = std :: min (c[n], _f[i]);
                    if (!is[_v[i]]) q[++ t] = _v[i], is[_v[i]] = true; 
                }
        return d[T] < INF;
    }
    int Do () { 
        int res = 0, p = 0; rg int i;
        for (int x; Bfs (); ++ p) {
            for (x = c[T], i = T; i != S; i = _v[pre[i] ^ 1])
                _f[pre[i]] -= x, _f[pre[i] ^ 1] += x;
            res += d[T] * x;
        }
        printf ("%d %d", p, res);
    }
}
int main (int argc, char *argv[]) { 
    int N, M; read (N), read (M); rg int i;
    S = 1, T = N << 1; int x, y, z;
    net :: In (S, S + N, INF, 0), net :: In (N, T, INF, 0);
    for (i = 1; i <= M; ++ i) read (x), read (y), read (z), net :: In (N + x, y, 1, z);
    for (i = 2; i < N; ++ i) net :: In (i, i + N, 1, 0);
    net :: Do ();
    return 0;
}

 

posted @ 2018-01-19 21:22  ZlycerQan  阅读(...)  评论(...编辑  收藏