#include #define REP_(i, a_, b_, a, b, ...) \ for (int i = (a), END_##i = (b); i < END_##i; ++i) #define REP(i, ...) REP_(i, __VA_ARGS__, __VA_ARGS__, 0, __VA_ARGS__) #define ALL(x) std::begin(x), std::end(x) using i64 = long long; template inline bool chmax(T &a, U b) { return a < b and ((a = std::move(b)), true); } template inline bool chmin(T &a, U b) { return a > b and ((a = std::move(b)), true); } template inline int ssize(const T &a) { return (int) std::size(a); } template std::istream &operator>>(std::istream &is, std::vector &a) { for (auto &x: a) is >> x; return is; } template std::ostream &operator<<(std::ostream &os, const std::pair &a) { return os << "(" << a.first << ", " << a.second << ")"; } template std::ostream &print_seq(const Container &a, std::string_view sep = " ", std::string_view ends = "\n", std::ostream &os = std::cout) { auto b = std::begin(a), e = std::end(a); for (auto it = std::begin(a); it != e; ++it) { if (it != b) os << sep; os << *it; } return os << ends; } template struct is_iterable : std::false_type {}; template struct is_iterable())), decltype(std::end(std::declval()))>> : std::true_type { }; template::value && !std::is_same::value && !std::is_same::value>> std::ostream &operator<<(std::ostream &os, const T &a) { return print_seq(a, ", ", "", (os << "{")) << "}"; } void print() { std::cout << "\n"; } template void print(const T &x) { std::cout << x << "\n"; } template void print(const Head &head, Tail... tail) { std::cout << head << " "; print(tail...); } struct Input { template operator T() const { T x; std::cin >> x; return x; } } in; #ifdef MY_DEBUG #include "debug_dump.hpp" #else #define DUMP(...) #endif using namespace std; template struct Infinity { template constexpr operator T() const { static_assert(sign == 1 or not std::is_unsigned_v, "must be positive in an unsigned type"); if constexpr (std::numeric_limits::has_infinity) { return T(sign) * std::numeric_limits::infinity(); } else { return T(sign) * (std::numeric_limits::max() / T(2)); } } constexpr Infinity operator-() const { return {}; } template friend constexpr bool operator==(const T &x, const Infinity &y) { return x == T(y); } template friend constexpr bool operator!=(const T &x, const Infinity &y) { return x != T(y); } }; constexpr Infinity<> kBig; template using MinHeap = priority_queue, greater>; struct Edge { i64 cost; int to; }; struct State { i64 cost; int node; }; bool operator>(const State &x, const State &y) { return x.cost > y.cost; } // Returns min distance from the start node to each node (if exists). auto search_shortest_path(const vector> &g, int start) { const int n = g.size(); auto mincost = vector(n, (i64) kBig); MinHeap que; auto push = [&](i64 cost, int node) -> bool { if (chmin(mincost[node], cost)) { que.push(State{cost, node}); return true; } return false; }; assert(push(0LL, start)); while (not que.empty()) { State cur = que.top(); que.pop(); if (cur.cost != mincost[cur.node]) continue; for (const auto &e: g[cur.node]) { auto new_cost = cur.cost + e.cost; push(new_cost, e.to); } } return mincost; } auto solve() { int n = in, m = in, S = in, G = in; vector> g(n); REP(i, m) { int a = in, b = in, c = in; g[a].push_back({c, b}); g[b].push_back({c, a}); } auto dist = search_shortest_path(g, G); int mind = dist[S]; DUMP(dist, mind); vector path; int cur = S; path.push_back(cur); while (cur != G) { int nex = kBig; for (const auto &e: g[cur]) { if (e.to >= nex) continue; if (mind - e.cost == dist[e.to]) { nex = e.to; } } assert(nex != kBig); path.push_back(nex); cur = nex; mind = dist[cur]; } return path; } auto main() -> int { ios_base::sync_with_stdio(false), cin.tie(nullptr); cout << std::fixed << std::setprecision(18); const int t = 1; REP(test_case, t) { auto ans = solve(); print_seq(ans); } }