上下界最大流

用法

• add(u, v, l, r, c)：连一条容量在 \([l, r]\) 的从 \(u\) 到 \(v\) 的边；
• solve()：检查是否存在无源汇可行流；
• solve(s, t)：计算有源汇最大流。

#define add add0
#include "flow-max.cpp"
#undef add
namespace Dinic{
  int G[MAXN];
  void add(int u, int v, int l, int r){
    G[v] += l, G[u] -= l;
    add0(u, v, r - l);
  }
  void clear(){
    for(int i = 1;i <= t;++ i){
      N[i] = F[i] = V[i] = 0;
    }
    for(int i = 1;i <= n;++ i){
      H[i] = G[i] = C[i] = 0;
    }
    t = 1, n = 0;
  }
  bool solve(){ // 为真表示有解
    int s = ++ n, t = ++ n;
    i64 sum = 0;
    for(int i = 1;i <= n - 2;++ i){
      if(G[i] < 0)
        add0(i, t, -G[i]);
      else
        add0(s, i,  G[i]), sum += G[i];
    }
    return sum != dinic(s, t);
  }
  i64 solve(int s0, int t0){
    add0(t0, s0, INF);
    int s = ++ n, t = ++ n;
    i64 sum = 0;
    for(int i = 1;i <= n - 2;++ i){
      if(G[i] < 0)
        add0(i, t, -G[i]);
      else
        add0(s, i,  G[i]), sum += G[i];
    }
    return dinic(s, t) == sum ? dinic(s0, t0) : -1;
  }
}