4. Kingdom Defence.cpp

#include <iostream>

#include <boost/graph/adjacency_list.hpp>
// BGL flow include *NEW*
#include <boost/graph/push_relabel_max_flow.hpp>


typedef boost::adjacency_list_traits<boost::vecS, boost::vecS, boost::directedS> traits;
typedef boost::adjacency_list<boost::vecS, boost::vecS, boost::directedS, boost::no_property,
  boost::property<boost::edge_capacity_t, long,
    boost::property<boost::edge_residual_capacity_t, long,
      boost::property<boost::edge_reverse_t, traits::edge_descriptor>>>> graph;
typedef traits::vertex_descriptor vertex_desc;
typedef traits::edge_descriptor edge_desc;

class edge_adder {
  graph &G;

 public:
  explicit edge_adder(graph &G) : G(G) {}
  void add_edge(int from, int to, long capacity) {
    auto c_map = boost::get(boost::edge_capacity, G);
    auto r_map = boost::get(boost::edge_reverse, G);
    const auto e = boost::add_edge(from, to, G).first;
    const auto rev_e = boost::add_edge(to, from, G).first;
    c_map[e] = capacity;
    c_map[rev_e] = 0; // reverse edge has no capacity!
    r_map[e] = rev_e;
    r_map[rev_e] = e;
  }
};

void testcase() {
  int l, p; std::cin >> l >> p;
  
  graph G(l);
  edge_adder adder(G);
  
  const vertex_desc v_source = boost::add_vertex(G);
  const vertex_desc v_sink = boost::add_vertex(G);
  
  int ns = 0;
  
  for (int i= 0; i < l; ++i) {
    int g, d; std::cin >> g >> d;
    adder.add_edge(v_source, i, g);
    adder.add_edge(i, v_sink, d);
    ns += d;
  }
  
  for (int i = 0; i< p; ++i) {
    int f, t, c, C; std::cin >> f >> t >> c >> C;
    int d = C-c;
    if (c > 0) {
      ns += c;
      adder.add_edge(f, v_sink, c);
      adder.add_edge(v_source, t, c);
    }
    if (d > 0) {
      adder.add_edge(f, t, d);
    }
  }
  
  long flow = boost::push_relabel_max_flow(G, v_source, v_sink);
  
  if (flow == ns) std::cout << "yes\n";
  else std::cout << "no\n";
}

int main() {
  std::ios_base::sync_with_stdio(false);
  int t; std::cin >> t;
  while(t--) testcase();
}