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@@ -0,0 +1,45 @@
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+#include <cstdio>
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+#include <cstring>
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+#include <queue>
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+#include <vector>
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+
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+using namespace std;
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+
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+const int N = 30000;
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+const int M = 150000;
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+const int INF = 0x3F3F3F3F;
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+
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+int dist[N + 1];
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+
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+struct E {
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+ int v;
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+ int c;
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+ E(int v, int c) : v(v), c(c) {}
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+ bool operator<(const E &that) const { return this->c > that.c; }
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+};
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+
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+int main() {
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+ int n, m, a, b, c, t;
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+ scanf("%d %d", &n, &m);
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+ memset(dist, 0x3F, sizeof(dist));
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+ vector<vector<E>> adj(n + 1);
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+ for (int i = 0; i < m; i++) {
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+ scanf("%d %d %d", &a, &b, &c);
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+ adj[a].push_back(E(b, c));
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+ }
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+ priority_queue<E> pq;
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+ dist[1] = 0, t = 1;
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+ for (int i = 0; i < adj[1].size(); i++) pq.push(adj[1][i]);
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+ while (t < n) {
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+ E e = pq.top();
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+ pq.pop();
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+ if (dist[e.v] <= e.c) continue;
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+ dist[e.v] = e.c;
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+ vector<E>::iterator it;
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+ for (it = adj[e.v].begin(); it != adj[e.v].end(); ++it)
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+ if (dist[it->v] == INF) pq.push(E(it->v, e.c + it->c));
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+ t++;
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+ }
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+ printf("%d\n", dist[n]);
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+ return 0;
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+}
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