起点和终点各做一次单源最短路, d1[i], d2[i]分别代表起点到i点的最短路和终点到i点的最短路,枚举商业线车票cost(a, b); ans = min( d1[a] + cost(a, b) + d2[b] );
#include <cstdio> #include <cstring> #include <cstdlib> #include <algorithm> #include <vector> #include <queue> using namespace std; const int MAXN = 1010; const int INF = 1 << 22; struct HeapNode { int d, u; HeapNode() { } HeapNode( int _d, int _u ): d(_d), u(_u) { } bool operator<( const HeapNode& rhs ) const { return d > rhs.d; } }; struct Edge { int from, to, dist; Edge() { } Edge( int f, int t, int d ) : from(f), to(t), dist(d) { } }; int N, S, E; struct Dijkstra { int n, m; vector<Edge> edges; vector<int> G[MAXN]; bool done[MAXN]; int d1[MAXN]; int d2[MAXN]; int p1[MAXN]; int p2[MAXN]; void init( int n ) { this->n = n; for ( int i = 0; i <= n; ++i ) G[i].clear(); edges.clear(); return; } void AddEdge( int from, int to, int dist ) { edges.push_back( Edge( from, to, dist ) ); m = edges.size(); G[from].push_back(m - 1); return; } void dijkstra( int s, int *d, int *p ) { priority_queue<HeapNode> Q; for ( int i = 0; i <= n; ++i ) d[i] = INF; d[s] = 0; memset( done, 0, sizeof(done) ); Q.push( HeapNode( 0, s ) ); while ( !Q.empty() ) { HeapNode x = Q.top(); Q.pop(); int u = x.u; if ( done[u] ) continue; done[u] = true; for ( int i = 0; i < G[u].size(); ++i ) { Edge& e = edges[ G[u][i] ]; if ( d[e.to] > d[u] + e.dist ) { d[e.to] = d[u] + e.dist; p[e.to] = G[u][i]; Q.push( HeapNode( d[e.to], e.to ) ); } } } return; } void Print1( int e ) { if ( e == S ) { printf( "%d", S ); return; } Edge& tp = edges[ p1[e] ]; Print1( tp.from ); printf( " %d", e ); return; } void Print2( int e ) { if ( e == E ) { printf( " %d", E ); return; } Edge& tp = edges[ p2[e] ]; printf( " %d", e ); Print2( tp.from ); return; } }; int M, K; Dijkstra slv; vector<Edge> ec; //经济线路 int main() { //freopen( "UVa_11374.in", "r", stdin ); //freopen( "UVa_11374.out", "w", stdout ); int cas = 0; while ( scanf( "%d%d%d", &N, &S, &E ) == 3 ) { slv.init( N ); scanf( "%d", &M ); for ( int i = 0; i < M; ++i ) { int u, v, cost; scanf( "%d%d%d", &u, &v, &cost ); slv.AddEdge( u, v, cost ); slv.AddEdge( v, u, cost ); } ec.clear(); scanf( "%d", &K ); for ( int i = 0; i < K; ++i ) { int u, v, cost; scanf( "%d%d%d", &u, &v, &cost ); ec.push_back( Edge(u, v, cost) ); } slv.dijkstra( S, slv.d1, slv.p1 ); slv.dijkstra( E, slv.d2, slv.p2 ); // for ( int i = 1; i <= N; ++i ) // { // printf("%d %d ", slv.d1[i], slv.d2[i] ); // } int ans = slv.d1[E]; int huan = -1; int huaned; for ( int i = 0; i < K; ++i ) { int u = ec[i].from; int v = ec[i].to; int tmp1 = slv.d1[u] + ec[i].dist + slv.d2[v]; int tmp2 = slv.d1[v] + ec[i].dist + slv.d2[u]; if ( tmp1 < ans ) { ans = tmp1; huan = u; huaned = v; } if ( tmp2 < ans ) { ans = tmp2; huan = v; huaned = u; } } if (cas) puts(""); ++cas; if ( huan == -1 ) { slv.Print1(E); puts(""); puts("Ticket Not Used"); } else { slv.Print1(huan); slv.Print2(huaned); puts(""); printf( "%d ", huan ); } printf( "%d ", ans ); } return 0; }