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algorithm.cpp
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algorithm.cpp
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#include <limits>
#include <iostream>
#include <iomanip>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
// BGL include
#include <boost/graph/adjacency_list.hpp>
// BGL flow include *NEW*
#include <boost/graph/push_relabel_max_flow.hpp>
// Graph Type with nested interior edge properties for flow algorithms
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;
// Custom edge adder class, highly recommended
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;
int src = l, dst = l + 1;
graph g(l + 2);
edge_adder adder(g);
std::vector<int> supply(l, 0);
for (int i = 0; i < l; i++) {
int g, d; std::cin >> g >> d;
supply[i] = g - d;
}
for (int i = 0; i < p; i++) {
int f, t, min, max; std::cin >> f >> t >> min >> max;
supply[f] -= min;
supply[t] += min;
adder.add_edge(f, t, max - min);
}
int tot = 0;
for (int i = 0; i < l; i++) {
if (supply[i] > 0)
adder.add_edge(src, i, supply[i]);
else {
tot -= supply[i];
adder.add_edge(i, dst, -supply[i]);
}
}
long flow = boost::push_relabel_max_flow(g, src, dst);
std::cout << ((flow == tot) ? "yes" : "no") << std::endl;
}
int main() {
std::ios_base::sync_with_stdio(false);
int t;
std::cin >> t;
for (int i = 0; i < t; ++i)
testcase();
}