sotanishy's code snippets for competitive programming
View the Project on GitHub sotanishy/cp-library-cpp
#define PROBLEM "https://judge.yosupo.jp/problem/shortest_path" #include "../../graph/shortest_path.hpp" #include <bits/stdc++.h> using namespace std; using ll = long long; int main() { ios_base::sync_with_stdio(false); cin.tie(nullptr); int N, M, s, t; cin >> N >> M >> s >> t; vector<vector<pair<int, long long>>> G(N); for (int i = 0; i < M; ++i) { int a, b, c; cin >> a >> b >> c; G[a].push_back({b, c}); } auto [dist, par] = shortest_path_tree(G, s); if (dist[t] >= 1e18) { cout << -1 << endl; } else { vector<int> path; for (int v = t; v != s; v = par[v]) { path.push_back(v); } path.push_back(s); reverse(path.begin(), path.end()); cout << dist[t] << " " << path.size() - 1 << endl; for (int i = 0; i < (int)path.size() - 1; ++i) { cout << path[i] << " " << path[i + 1] << "\n"; } } }
#line 1 "test/yosupo/shortest_path.test.cpp" #define PROBLEM "https://judge.yosupo.jp/problem/shortest_path" #line 2 "graph/shortest_path.hpp" #include <limits> #include <queue> #include <tuple> #include <utility> #include <vector> /* * Bellman-Ford Algorithm */ template <typename T> std::vector<T> bellman_ford(const std::vector<std::tuple<int, int, T>>& G, int V, int s) { constexpr T INF = std::numeric_limits<T>::max(); std::vector<T> dist(V, INF); dist[s] = 0; for (int i = 0; i < V; ++i) { for (auto& [s, t, w] : G) { if (dist[s] != INF && dist[t] > dist[s] + w) { dist[t] = dist[s] + w; if (i == V - 1) return {}; } } } return dist; } /* * Floyd-Warshall Algorithm */ template <typename T> void floyd_warshall(std::vector<std::vector<T>>& dist) { const int V = dist.size(); for (int k = 0; k < V; ++k) { for (int i = 0; i < V; ++i) { for (int j = 0; j < V; ++j) { dist[i][j] = std::min(dist[i][j], dist[i][k] + dist[k][j]); } } } } /* * Dijkstra's Algorithm */ template <typename T> std::vector<T> dijkstra(const std::vector<std::vector<std::pair<int, T>>>& G, int s) { std::vector<T> dist(G.size(), std::numeric_limits<T>::max()); dist[s] = 0; using P = std::pair<T, int>; std::priority_queue<P, std::vector<P>, std::greater<P>> pq; pq.emplace(0, s); while (!pq.empty()) { auto [d, v] = pq.top(); pq.pop(); if (dist[v] < d) continue; for (auto& [u, w] : G[v]) { if (dist[u] > d + w) { dist[u] = d + w; pq.emplace(dist[u], u); } } } return dist; } template <typename T> std::pair<std::vector<T>, std::vector<int>> shortest_path_tree( const std::vector<std::vector<std::pair<int, T>>>& G, int s) { std::vector<T> dist(G.size(), std::numeric_limits<T>::max()); std::vector<int> par(G.size(), -1); dist[s] = 0; using P = std::pair<T, int>; std::priority_queue<P, std::vector<P>, std::greater<P>> pq; pq.emplace(0, s); while (!pq.empty()) { auto [d, v] = pq.top(); pq.pop(); if (dist[v] < d) continue; for (auto& [u, w] : G[v]) { if (dist[u] > d + w) { dist[u] = d + w; par[u] = v; pq.emplace(dist[u], u); } } } return {dist, par}; } /* * Breadth-First Search */ std::vector<int> bfs(const std::vector<std::vector<int>>& G, int s) { std::vector<int> dist(G.size(), -1); dist[s] = 0; std::queue<int> que; que.push(s); while (!que.empty()) { int v = que.front(); que.pop(); for (int u : G[v]) { if (dist[u] == -1) { dist[u] = dist[v] + 1; que.push(u); } } } return dist; } /* * Dial's Algorithm */ std::vector<int> dial(const std::vector<std::vector<std::pair<int, int>>>& G, int s, int w) { std::vector<int> dist(G.size(), std::numeric_limits<int>::max()); dist[s] = 0; std::vector<std::vector<int>> buckets(w * G.size(), std::vector<int>()); buckets[0].push_back(s); for (int d = 0; d < (int)buckets.size(); ++d) { while (!buckets[d].empty()) { int v = buckets[d].back(); buckets[d].pop_back(); if (dist[v] < d) continue; for (auto& [u, w] : G[v]) { if (dist[u] > d + w) { dist[u] = d + w; buckets[dist[u]].push_back(u); } } } } return dist; } #line 4 "test/yosupo/shortest_path.test.cpp" #include <bits/stdc++.h> using namespace std; using ll = long long; int main() { ios_base::sync_with_stdio(false); cin.tie(nullptr); int N, M, s, t; cin >> N >> M >> s >> t; vector<vector<pair<int, long long>>> G(N); for (int i = 0; i < M; ++i) { int a, b, c; cin >> a >> b >> c; G[a].push_back({b, c}); } auto [dist, par] = shortest_path_tree(G, s); if (dist[t] >= 1e18) { cout << -1 << endl; } else { vector<int> path; for (int v = t; v != s; v = par[v]) { path.push_back(v); } path.push_back(s); reverse(path.begin(), path.end()); cout << dist[t] << " " << path.size() - 1 << endl; for (int i = 0; i < (int)path.size() - 1; ++i) { cout << path[i] << " " << path[i + 1] << "\n"; } } }