// URL: https://yukicoder.me/problems/no/160 import std.algorithm, std.array, std.bitmanip, std.container, std.conv, std.format, std.functional, std.math, std.range, std.traits, std.typecons, std.stdio, std.string; version(unittest) {} else void main() { int N, M, S, G; io.getV(N, M, S, G); auto g = GraphW!int(N); foreach (_; 0..M) { int a, b, c; io.getV(a, b, c); g.addEdgeB(a, b, c); } auto d = g.dijkstra(G).dist; auto r = [S], t = 0; while (r.back != G) { auto nt = t, nv = N; foreach (e; g[r.back]) { if (t+e.wt+d[e.dst] != d[S]) continue; if (e.dst < nv) { nt = e.wt; nv = e.dst; } } t += nt; r ~= nv; } io.put(r); } struct Graph { alias Node = int; Node n; Node[][] g; alias g this; pure nothrow @safe { this(Node n) { this.n = n; g = new Node[][](n); } void addEdge(Node u, Node v) in { assert(0 <= u && u < n && 0 <= v && v < n); } do { g[u] ~= v; } void addEdgeB(Node u, Node v) in { assert(0 <= u && u < n && 0 <= v && v < n); } do { g[u] ~= v; g[v] ~= u; } } } struct GraphW(W = int, W i = 10^^9) { alias Node = int, Wt = W, inf = i; struct Edge { Node src, dst; Wt wt; alias cap = wt; } Node n; Edge[][] g; alias g this; pure nothrow @safe { this(Node n) { this.n = n; g = new Edge[][](n); } void addEdge(Node u, Node v, Wt w) in { assert(0 <= u && u < n && 0 <= v && v < n); } do { g[u] ~= Edge(u, v, w); } void addEdgeB(Node u, Node v, Wt w) in { assert(0 <= u && u < n && 0 <= v && v < n); } do { g[u] ~= Edge(u, v, w); g[v] ~= Edge(v, u, w); } } } struct GraphM(W = int, W i = 10^^9) { alias Node = int, Wt = W, inf = i; Node n; Wt[][] g; alias g this; pure nothrow @safe { this(int n) { this.n = n; g = new Wt[][](n, n); } static GraphM!(W, i) init(Node n) { auto g = GraphM!(W, i)(n); foreach (i; 0..n) { g[i][] = inf; g[i][i] = 0; } return g; } } } struct Dijkstra(Graph) { alias Node = Graph.Node, Wt = Graph.Wt, Edge = Graph.Edge; Graph g; alias g this; Wt[] dist; Node[] prev; pure { @trusted this(Graph g, Node s) in { assert(0 <= s && s < g.n); } do { this.g = g; auto sent = n; dist = new Wt[](n); dist[] = g.inf; dist[s] = 0; prev = new Node[](n); prev[] = sent; auto q = heapify!("a.wt>b.wt")(Array!Edge(Edge(sent, s, 0))); while (!q.empty) { auto e = q.front; q.removeFront(); if (prev[e.dst] != sent) continue; prev[e.dst] = e.src; foreach (f; g[e.dst]) { auto w = e.wt+f.wt; if (dist[f.dst] > w) { dist[f.dst] = w; q.insert(Edge(f.src, f.dst, w)); } } } } } } pure { @trusted auto dijkstra(Graph, Node)(Graph g, Node s) in { assert(0 <= s && s < g.n); } do { return Dijkstra!Graph(g, s); } } auto io = IO!()(); import std.stdio; struct IO(alias IN = stdin, alias OUT = stdout) { import std.meta : allSatisfy; import core.stdc.stdlib : exit; void getV(T...)(ref T v) { foreach (ref w; v) get(w); } void getA(T)(size_t n, ref T v) if (hasAssignableElements!T) { v = new T(n); foreach (ref w; v) get(w); } void getC(T...)(size_t n, ref T v) if (allSatisfy!(hasAssignableElements, T)) { foreach (ref w; v) w = new typeof(w)(n); foreach (i; 0..n) foreach (ref w; v) get(w[i]); } void getM(T)(size_t r, size_t c, ref T v) if (hasAssignableElements!T && hasAssignableElements!(ElementType!T)) { v = new T(r); foreach (ref w; v) getA(c, w); } template getS(E...) { void getS(T)(size_t n, ref T v) { v = new T(n); foreach (ref w; v) foreach (e; E) mixin("get(w."~e~");"); } } const struct PutConf { bool newline = true, flush, exit; string floatFormat = "%.10f", delimiter = " "; } void put(alias conf = "{}", T...)(T v) { mixin("const PutConf c = "~conf~"; putMain!c(v);"); } void putB(alias conf = "{}", S, T)(bool c, S t, T f) { if (c) put!conf(t); else put!conf(f); } void putRaw(T...)(T v) { OUT.write(v); OUT.writeln; } private { dchar[] buf; auto sp = (new dchar[](0)).splitter; void nextLine() { IN.readln(buf); sp = buf.splitter; } void get(T)(ref T v) { if (sp.empty) nextLine(); v = sp.front.to!T; sp.popFront(); } void putMain(PutConf c, T...)(T v) { foreach (i, w; v) { putOne!c(w); if (i+1 < v.length) OUT.write(c.delimiter); } static if (c.newline) OUT.writeln; static if (c.flush) OUT.flush(); static if (c.exit) exit(0); } void putOne(PutConf c, T)(T v) { static if (isInputRange!T && !isSomeString!T) putRange!c(v); else static if (isFloatingPoint!T) OUT.write(format(c.floatFormat, v)); else static if (hasMember!(T, "fprint")) v.fprint(OUT); else OUT.write(v); } void putRange(PutConf c, T)(T v) { auto w = v; while (!w.empty) { putOne!c(w.front); w.popFront(); if (!w.empty) OUT.write(c.delimiter); } } } }