843MS,差点就超时!
/* Name: 最短路(bellmanFord) Copyright: Author: Try_86 Date: 11/04/12 20:39 Description: 建反向图,求终点到各点的最短路 */ #include <cstdio> #include <iostream> using namespace std; const int N = 1005; const int M = 40005; const int MAX = 1000000000; int dis[N]; struct edge { int u; int v; int w; }e[M]; void init(int vs, int s) { for (int i=1; i<=vs; ++i) dis[i] = MAX; dis[s] = 0; return ; } void relax(int u, int v, int w) { if (dis[v] > dis[u] + w) dis[v] = dis[u] + w; return ; } void bellmanFord(int es, int vs, int s) { init(vs, s); for (int i=1; i<vs; ++i) { for (int j=0; j<es; ++j) relax(e[j].u, e[j].v, e[j].w); } return ; } int main() { int n, m, end; while (scanf("%d%d%d", &n, &m, &end) != EOF) { for (int i=0; i<m; ++i) scanf ("%d%d%d", &e[i].v, &e[i].u, &e[i].w); bellmanFord(m, n, end); int cs, s, maxs; maxs = MAX; scanf ("%d", &cs); for (int i=0; i<cs; ++i) { scanf ("%d", &s); if (maxs > dis[s]) maxs = dis[s]; } if (maxs != MAX) printf ("%d\n", maxs); else printf ("-1\n"); } return 0; }