CP-Algorithms Library

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View the Project on GitHub cp-algorithms/cp-algorithms-aux

:heavy_check_mark: Shortest Path (verify/graph/shortest_path.test.cpp)

Depends on

Code

// @brief Shortest Path
#define PROBLEM "https://judge.yosupo.jp/problem/shortest_path"
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2")
#include "cp-algo/graph/shortest_path.hpp"
#include <bits/stdc++.h>

using namespace std;
using namespace cp_algo::graph;

void solve() {
    int n, m, s, t;
    cin >> n >> m >> s >> t;
    weighted_digraph g(n);
    g.read_edges(m);
    auto opath = shortest_path(g, s, t);
    if(!opath) {
        cout << -1 << "\n";
    } else {
        auto [d, path] = *opath;
        cout << d << ' ' << size(path) << "\n";
        int v = s;
        for(auto e: path) {
            int w = g.edge(e).traverse(v);
            cout << exchange(v, w) << ' ' << w << "\n";
        }
    }
}

signed main() {
    //freopen("input.txt", "r", stdin);
    ios::sync_with_stdio(0);
    cin.tie(0);
    int t = 1;
    //cin >> t;
    while(t--) {
        solve();
    }
}

#line 1 "verify/graph/shortest_path.test.cpp"
// @brief Shortest Path
#define PROBLEM "https://judge.yosupo.jp/problem/shortest_path"
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2")
#line 1 "cp-algo/graph/shortest_path.hpp"


#line 1 "cp-algo/graph/base.hpp"


#line 1 "cp-algo/graph/edge_types.hpp"


#include <iostream>
#include <cstdint>
namespace cp_algo::graph {
    using node_index = int;
    struct edge_base {
        int xor_nodes;

        edge_base() {}
        edge_base(node_index from, node_index to): xor_nodes(from ^ to) {}

        // Given one endpoint, return the other
        node_index traverse(node_index from) const {
            return xor_nodes ^ from;
        }

        static auto read(node_index v0 = 0) {
            node_index u, v;
            std::cin >> u >> v;
            u -= v0;
            v -= v0;
            return std::pair{u, edge_base(u, v)};
        }
    };

    struct weighted_edge: edge_base {
        int64_t w;

        weighted_edge() {}
        weighted_edge(node_index from, node_index to, int64_t w): edge_base(from, to), w(w) {}

        static auto read(node_index v0 = 0) {
            auto [u, e] = edge_base::read(v0);
            int64_t w;
            std::cin >> w;
            return std::pair{u, weighted_edge(u, e.traverse(u), w)};
        }
    };

    template<typename edge>
    concept edge_type = std::is_base_of_v<edge_base, edge>;
    template<typename edge>
    concept weighted_edge_type = std::is_base_of_v<weighted_edge, edge>;
}

#line 1 "cp-algo/graph/concepts.hpp"


#line 4 "cp-algo/graph/concepts.hpp"
#include <type_traits>

namespace cp_algo::graph {
    // Shared graph mode enum for all graph headers
    enum graph_mode { directed, undirected };
    // Traits: true for types that expose `edge_t` and static `mode`
    template<typename T, typename = void>
    struct graph_traits : std::false_type {};

    template<typename T>
        requires requires { typename T::edge_t; T::mode; }
    struct graph_traits<T> : std::true_type {
        using edge_t = typename T::edge_t;
        static constexpr auto mode = T::mode;
        static constexpr bool is_directed = mode == directed;
        static constexpr bool is_undirected = mode == undirected;
        static constexpr bool is_weighted = weighted_edge_type<edge_t>;
    };

    // Concepts
    template<typename G>
    concept graph_type = graph_traits<G>::value;

    template<typename G>
    concept digraph_type = graph_type<G> && graph_traits<G>::is_directed;

    template<typename G>
    concept undirected_graph_type = graph_type<G> && graph_traits<G>::is_undirected;

    template<typename G>
    concept weighted_graph_type = graph_type<G> && graph_traits<G>::is_weighted;

    template<typename G>
    concept weighted_digraph_type = digraph_type<G> && graph_traits<G>::is_weighted;

    template<typename G>
    concept weighted_undirected_graph_type = undirected_graph_type<G> && graph_traits<G>::is_weighted;
}

#line 1 "cp-algo/structures/stack_union.hpp"


#line 1 "cp-algo/util/big_alloc.hpp"



#include <set>
#include <map>
#include <deque>
#include <stack>
#include <queue>
#include <vector>
#include <string>
#include <cstddef>
#include <bit>
#line 14 "cp-algo/util/big_alloc.hpp"
#include <forward_list>

// Single macro to detect POSIX platforms (Linux, Unix, macOS)
#if defined(__linux__) || defined(__unix__) || (defined(__APPLE__) && defined(__MACH__))
#define CP_ALGO_USE_MMAP 1
#include <sys/mman.h>
#else
#define CP_ALGO_USE_MMAP 0
#endif

namespace cp_algo {
    template<typename T, size_t Align = 32>
    class big_alloc {
        static_assert(Align >= alignof(void*), "Align must be at least pointer-size");
        static_assert(std::has_single_bit(Align), "Align must be a power of two");

    public:
        using value_type = T;
        template<class U>
        struct rebind {
            using other = big_alloc<U, Align>;
        };
        constexpr bool operator==(const big_alloc&) const = default;

        big_alloc() noexcept = default;
        template<typename U, std::size_t A>
        big_alloc(const big_alloc<U, A>&) noexcept {}

        [[nodiscard]] T* allocate(std::size_t n) {
            std::size_t padded = round_up(n * sizeof(T));
            std::size_t align = std::max<std::size_t>(alignof(T), Align);
#if CP_ALGO_USE_MMAP
            if(padded >= MEGABYTE) {
                void* raw = mmap(nullptr, padded, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
                madvise(raw, padded, MADV_HUGEPAGE);
                return static_cast<T*>(raw);
            }
#endif
            return static_cast<T*>(::operator new(padded, std::align_val_t(align)));
        }

        void deallocate(T* p, std::size_t n) noexcept {
            if(!p) {
                return;
            }
            std::size_t padded = round_up(n * sizeof(T));
            std::size_t align = std::max<std::size_t>(alignof(T), Align);
#if CP_ALGO_USE_MMAP
            if(padded >= MEGABYTE) {
                munmap(p, padded);
                return;
            }
#endif
            ::operator delete(p, padded, std::align_val_t(align));
        }

    private:
        static constexpr std::size_t MEGABYTE = 1 << 20;
        static constexpr std::size_t round_up(std::size_t x) noexcept {
            return (x + Align - 1) / Align * Align;
        }
    };

    template<typename T>
    using big_vector = std::vector<T, big_alloc<T>>;
    template<typename T>
    using big_basic_string = std::basic_string<T, std::char_traits<T>, big_alloc<T>>;
    template<typename T>
    using big_deque = std::deque<T, big_alloc<T>>;
    template<typename T>
    using big_stack = std::stack<T, big_deque<T>>;
    template<typename T>
    using big_queue = std::queue<T, big_deque<T>>;
    template<typename T>
    using big_priority_queue = std::priority_queue<T, big_vector<T>>;
    template<typename T>
    using big_forward_list = std::forward_list<T, big_alloc<T>>;
    using big_string = big_basic_string<char>;

    template<typename Key, typename Value, typename Compare = std::less<Key>>
    using big_map = std::map<Key, Value, Compare, big_alloc<std::pair<const Key, Value>>>;
    template<typename T, typename Compare = std::less<T>>
    using big_multiset = std::multiset<T, Compare, big_alloc<T>>;
    template<typename T, typename Compare = std::less<T>>
    using big_set = std::set<T, Compare, big_alloc<T>>;
}


#line 5 "cp-algo/structures/stack_union.hpp"
#include <iterator>
#include <ranges>
namespace cp_algo::structures {
    template<class datatype>
    struct stack_union {
        stack_union(int n = 0): head(n), next(1), data(1) {}

        void push(int v, datatype const& vdata) {
            next.push_back(head[v]);
            head[v] = (int)std::size(next) - 1;
            data.push_back(vdata);
        }
        template<typename... Args>
        void emplace(int v, Args&&... vdata) {
            next.push_back(head[v]);
            head[v] = (int)std::size(next) - 1;
            data.emplace_back(std::forward<Args>(vdata)...);
        }

        void reserve(int m) {
            data.reserve(m);
            next.reserve(m);
        }

        size_t size() const {return std::size(head);}
        size_t nodes() const {return std::size(data);}

        template<typename Su>
        struct _iterator {
            using value_type = std::conditional_t<std::is_const_v<Su>, const datatype, datatype>;
            using difference_type = std::ptrdiff_t;

            Su* su = nullptr;
            int sv = 0;

            value_type& operator*() const { return su->data[sv]; }
            _iterator& operator++() { 
                sv = su->next[sv];
                return *this; 
            }
            _iterator operator++(int) { auto tmp = *this; ++*this; return tmp; }
            friend bool operator==(_iterator const& it, std::default_sentinel_t) { 
                return it.sv == 0;
            }
        };

        using iterator = _iterator<stack_union<datatype>>;
        using const_iterator = _iterator<const stack_union<datatype>>;

        auto operator[](this auto&& self, int v) {
            using Iter = _iterator<std::remove_reference_t<decltype(self)>>;
            return std::ranges::subrange(Iter{&self, self.head[v]}, std::default_sentinel);
        }

        big_vector<int> head, next;
        big_vector<datatype> data;
    };
}

#line 7 "cp-algo/graph/base.hpp"
namespace cp_algo::graph {
    using edge_index = int;
    template<edge_type _edge_t = edge_base, graph_mode _mode = undirected>
    struct graph {
        using edge_t = _edge_t;
        static constexpr auto mode = _mode;
        using incidence_list = structures::stack_union<edge_index>;
        graph(int n, int v0 = 0): v0(v0), adj(n) {}

        graph transpose() const {
            static_assert(mode == directed, "transpose is only defined for directed graphs");
            graph<edge_t, mode> gt(n(), v0);
            for(auto v: nodes()) {
                for(auto e: outgoing(v)) {
                    gt.add_edge(edge(e).traverse(v), edge(e));
                }
            }
            return gt;
        }
        edge_index add_edge(node_index u, edge_t e) {
            edge_index idx = (edge_index)size(E);
            E.push_back(e);
            adj.push(u, idx);
            if constexpr (mode == undirected) {
                adj.push(e.traverse(u), idx);
            }
            return idx;
        }
        edge_index add_edge(node_index u, auto... Args) {
            return add_edge(u, edge_t(u, Args...));
        }
        void read_edges(node_index m) {
            adj.reserve(mode == undirected ? 2 * m : m);
            for(edge_index i = 0; i < m; i++) {
                auto [u, e] = edge_t::read(v0);
                add_edge(u, e);
            }
        }
        auto outgoing(node_index v) const {return adj[v];}
        auto edges() const {return E | std::views::all;}
        auto nodes() const {return std::views::iota(node_index(0), n());}
        auto edge_indices() const {return std::views::iota(edge_index(0), m());}
        auto&& incidence_lists(this auto&& self) {return self.adj;}
        auto&& edge(this auto&& self, edge_index e) {return self.E[e];}
        node_index n() const {return (node_index)incidence_lists().size();}
        edge_index m() const {return (edge_index)edges().size();}
    private:
        node_index v0;
        big_vector<edge_t> E;
        incidence_list adj;
    };
    // aliases for most standard cases
    template<edge_type edge_t = edge_base>
    using digraph = graph<edge_t, directed>;
    template<weighted_edge_type edge_t = weighted_edge, graph_mode mode = undirected>
    using weighted_graph = graph<edge_t, mode>;
    template<weighted_edge_type edge_t = weighted_edge>
    using weighted_digraph = digraph<edge_t>;
}

#line 4 "cp-algo/graph/shortest_path.hpp"
#include <algorithm>
#line 6 "cp-algo/graph/shortest_path.hpp"
namespace cp_algo::graph {
    struct shortest_path_context {
        big_vector<int64_t> dist;
        big_vector<edge_index> pre;
        static constexpr int64_t inf = 1e18;
        shortest_path_context(int n)
            : dist(n, inf), pre(n) {}
    };

    struct dijkstra_context: shortest_path_context {
        struct que_t {
            int64_t dist;
            node_index v;
            bool operator<(que_t const& other) const {
                return dist > other.dist;
            }
        };
        big_priority_queue<que_t> pq;

        dijkstra_context(int n) : shortest_path_context(n) {}

        void push(node_index, edge_index, node_index v) {
            pq.push({dist[v], v});
        }

        std::optional<node_index> next_node() {
            while (!empty(pq)) {
                auto [dv, v] = pq.top();
                pq.pop();
                if (dv == dist[v]) {
                    return v;
                }
            }
            return std::nullopt;
        }
    };

    struct spfa_context: shortest_path_context {
        big_queue<node_index> que;
        big_vector<char> flags;
        static constexpr char in_queue = 1;
        static constexpr char invalidated = 2;

        spfa_context(int n) : shortest_path_context(n), flags(n) {}

        void push(node_index, edge_index, node_index v) {
            if (!(flags[v] & in_queue)) {
                que.push(v);
                flags[v] |= in_queue;
            }
        }

        std::optional<node_index> next_node() {
            while (!que.empty()) {
                node_index v = que.front();
                que.pop();
                flags[v] &= ~in_queue;
                if (!(flags[v] & invalidated)) {
                    return v;
                }
            }
            return std::nullopt;
        }
    };

    struct deep_spfa_context: spfa_context {
        struct traverse_edge {
            edge_index e;
            node_index v;
        };
        big_vector<big_basic_string<traverse_edge>> dependents;

        deep_spfa_context(int n) : spfa_context(n), dependents(n) {}

        void push(node_index u, edge_index e, node_index v) {
            invalidate_subtree(v);
            dependents[u].push_back({e, v});
            flags[v] &= ~invalidated;
            spfa_context::push(u, e, v);
        }

        void invalidate_subtree(node_index v) {
            big_vector<node_index> to_invalidate = {v};
            while (!empty(to_invalidate)) {
                node_index u = to_invalidate.back();
                to_invalidate.pop_back();
                flags[u] |= invalidated;
                flags[u] &= ~in_queue;
                for (auto [e, v]: dependents[u]) {
                    if (pre[v] == e) {
                        to_invalidate.push_back(v);
                    }
                }
                dependents[u].clear();
            }
        }
    };

    template<typename Context, weighted_graph_type graph>
    Context sssp_impl(graph const& g, node_index s) {
        Context context(g.n());
        context.dist[s] = 0;
        context.pre[s] = -1;
        context.push(s, -1, s);
        while(auto ov = context.next_node()) {
            node_index v = *ov;
            for(auto e: g.outgoing(v)) {
                node_index u = g.edge(e).traverse(v);
                auto w = g.edge(e).w;
                if(context.dist[v] + w < context.dist[u]) {
                    context.dist[u] = context.dist[v] + w;
                    context.pre[u] = e;
                    context.push(v, e, u);
                }
            }
        }
        return context;
    }

    template<weighted_graph_type graph>
    shortest_path_context dijkstra(graph const& g, node_index s) {
        return sssp_impl<dijkstra_context>(g, s);
    }
    template<weighted_graph_type graph>
    shortest_path_context spfa(graph const& g, node_index s) {
        return sssp_impl<spfa_context>(g, s);
    }
    template<weighted_graph_type graph>
    shortest_path_context deep_spfa(graph const& g, node_index s) {
        return sssp_impl<deep_spfa_context>(g, s);
    }
    
    template<weighted_graph_type graph>
    shortest_path_context single_source_shortest_path(graph const& g, node_index s) {
        bool negative_edges = std::ranges::any_of(g.edges(), [](auto const& e) { return e.w < 0; });
        return negative_edges ? deep_spfa(g, s) : dijkstra(g, s);
    }

    big_vector<edge_index> recover_path(auto const& g, auto const& pre, node_index s, node_index t) {
        big_vector<edge_index> path;
        node_index v = t;
        while(v != s) {
            path.push_back(pre[v]);
            v = g.edge(pre[v]).traverse(v);
        }
        std::ranges::reverse(path);
        return path;
    }

    template<weighted_graph_type graph>
    std::optional<std::pair<int64_t, big_vector<edge_index>>> shortest_path(graph const& g, node_index s, node_index t) {
        auto [dist, pre] = single_source_shortest_path(g, s);
        if (dist[t] == shortest_path_context::inf) {
            return std::nullopt;
        }
        return {{dist[t], recover_path(g, pre, s, t)}};
    }
}

#line 6 "verify/graph/shortest_path.test.cpp"
#include <bits/stdc++.h>

using namespace std;
using namespace cp_algo::graph;

void solve() {
    int n, m, s, t;
    cin >> n >> m >> s >> t;
    weighted_digraph g(n);
    g.read_edges(m);
    auto opath = shortest_path(g, s, t);
    if(!opath) {
        cout << -1 << "\n";
    } else {
        auto [d, path] = *opath;
        cout << d << ' ' << size(path) << "\n";
        int v = s;
        for(auto e: path) {
            int w = g.edge(e).traverse(v);
            cout << exchange(v, w) << ' ' << w << "\n";
        }
    }
}

signed main() {
    //freopen("input.txt", "r", stdin);
    ios::sync_with_stdio(0);
    cin.tie(0);
    int t = 1;
    //cin >> t;
    while(t--) {
        solve();
    }
}

Test cases

Env Name Status Elapsed Memory
g++ almost_line_00 :heavy_check_mark: AC 119 ms 24 MB
g++ almost_line_01 :heavy_check_mark: AC 119 ms 22 MB
g++ almost_line_02 :heavy_check_mark: AC 108 ms 24 MB
g++ example_00 :heavy_check_mark: AC 2 ms 4 MB
g++ example_01 :heavy_check_mark: AC 2 ms 4 MB
g++ grid_random_00 :heavy_check_mark: AC 89 ms 21 MB
g++ grid_swirl_00 :heavy_check_mark: AC 114 ms 24 MB
g++ line_00 :heavy_check_mark: AC 182 ms 30 MB
g++ max_dense_long_00 :heavy_check_mark: AC 62 ms 21 MB
g++ max_dense_random_00 :heavy_check_mark: AC 62 ms 21 MB
g++ max_dense_random_01 :heavy_check_mark: AC 64 ms 21 MB
g++ max_dense_zero_00 :heavy_check_mark: AC 57 ms 21 MB
g++ max_sparse_random_00 :heavy_check_mark: AC 73 ms 23 MB
g++ max_sparse_random_01 :heavy_check_mark: AC 114 ms 24 MB
g++ max_sparse_random_02 :heavy_check_mark: AC 113 ms 24 MB
g++ max_star_00 :heavy_check_mark: AC 136 ms 37 MB
g++ max_star_01 :heavy_check_mark: AC 153 ms 33 MB
g++ small_00 :heavy_check_mark: AC 2 ms 4 MB
g++ small_01 :heavy_check_mark: AC 2 ms 4 MB
g++ small_02 :heavy_check_mark: AC 2 ms 4 MB
g++ small_03 :heavy_check_mark: AC 2 ms 4 MB
g++ small_04 :heavy_check_mark: AC 2 ms 4 MB
g++ sparse_random_00 :heavy_check_mark: AC 60 ms 22 MB
g++ sparse_random_01 :heavy_check_mark: AC 62 ms 23 MB
g++ sparse_random_02 :heavy_check_mark: AC 71 ms 16 MB
g++ spfa_killer_00 :heavy_check_mark: AC 126 ms 31 MB
g++ wrong_dijkstra_handmade_00 :heavy_check_mark: AC 2 ms 4 MB
g++ wrong_dijkstra_killer_00 :heavy_check_mark: AC 113 ms 29 MB
g++ wrong_dijkstra_killer_01 :heavy_check_mark: AC 162 ms 26 MB
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