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-rw-r--r--2019/December/pump.cpp46
1 files changed, 46 insertions, 0 deletions
diff --git a/2019/December/pump.cpp b/2019/December/pump.cpp
new file mode 100644
index 0000000..20beb76
--- /dev/null
+++ b/2019/December/pump.cpp
@@ -0,0 +1,46 @@
+#include <bits/stdc++.h>
+#define f first
+#define s second
+using namespace std;
+typedef long long ll;
+typedef pair<int, int> ii;
+typedef vector<int> vi;
+typedef vector<ii> vii;
+constexpr int INF = 1e9;
+
+vector<pair<int, ii>> G[1001];
+
+int main() {
+ ifstream cin("pump.in");
+ ofstream cout("pump.out");
+
+ int N, M;
+ cin >> N >> M;
+ while (M--) {
+ int a, b, c, f;
+ cin >> a >> b >> c >> f;
+ G[a].emplace_back(b, ii(c, f));
+ G[b].emplace_back(a, ii(c, f));
+ }
+
+ int ans = 0;
+ for (int i = 1; i <= 1000; ++i) {
+ vi dist(N + 1, INF);
+ dist[1] = 0;
+ priority_queue<ii, vii, greater<ii>> pq;
+ pq.emplace(0, 1);
+ while (!pq.empty()) {
+ int d = pq.top().f, u = pq.top().s;
+ pq.pop();
+ if (d > dist[u]) continue;
+ for (auto& v : G[u]) {
+ if (v.s.s >= i && d + v.s.f < dist[v.f]) {
+ dist[v.f] = d + v.s.f;
+ pq.emplace(dist[v.f], v.f);
+ }
+ }
+ }
+ ans = max((int)1e6 * i / dist[N], ans);
+ }
+ cout << ans << '\n';
+}