<vector>;using std::make_pair;typedef pair<int, int> pii;priority_queue<pii, vector<pii>, greater<pii> >q;const int INF = 0x3f3f3f3f;const int maxn = 2e4;const int maxm = 1e5 + 5;int first[maxn];int u[maxm], v[maxm], w[maxm], next[maxm];int d[maxn];n, int m) {for (int i = 0; i < n; i++)first[i] = -1;m *= 2;for (int i = 0; i < m; i++) {scanf ("%d%d%d", &u[i], &v[i], &w[i]);next[i] = first[u[i]];first[u[i]] = i;i++;u[i] = v[i – 1];v[i] = u[i – 1];w[i] = w[i – 1];next[i] = first[u[i]];first[u[i]] = i;}}s, int t, int n) {for (int i = 0; i < n; i++)d[i] = (i == s) ? 0 : INF;q.push(make_pair(d[s],s));pii cur;while (!q.empty()) {cur = q.top();q.pop();if (cur.first != d[cur.second]) continue;for (int i = first[cur.second]; i != -1; i = next[i])if (d[v[i]] > d[u[i]] + w[i]) {d[v[i]] = d[u[i]] + w[i];q.push(make_pair(d[v[i]], v[i]));}}return d[t];}{int T;scanf ("%d", &T);int n, m, s, t, cas = 0;while (T–) {scanf ("%d%d%d%d", &n, &m, &s, &t);read_Graph(n, m);int ans = Dijkstra(s, t, n);if (ans == INF)printf ("Case #%d: unreachable\n", ++cas);;}return 0;}
，思念是对昨天悠长的沉淀和对未来美好的向往。
