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56 lines
1.2 KiB
56 lines
1.2 KiB
#include <bits/stdc++.h>
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using namespace std;
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typedef pair<int, int> PII;
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const int INF = 0x3f3f3f3f;
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const int N = 110;
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const int M = 2 * 210; // 无向图，需要开二倍的数组长度！
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int n, m;
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int h[N], e[M], w[M], ne[M], idx;
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void add(int a, int b, int c) {
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e[idx] = b, w[idx] = c, ne[idx] = h[a], h[a] = idx++;
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}
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int dis[N];
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bool st[N];
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int dijkstra() {
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memset(dis, 0x3f, sizeof dis);
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dis[1] = 0;
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priority_queue<PII, vector<PII>, greater<int>> q;
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q.push({0, 1});
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while (q.size()) {
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PII t = q.top();
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q.pop();
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int u = t.second;
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if (st[u]) continue;
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st[u] = true;
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for (int i = h[u]; ~i; i = ne[i]) {
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int v = e[i];
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if (dis[v] > dis[u] + w[i]) {
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dis[v] = dis[u] + w[i];
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q.push({dis[v], v});
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}
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}
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}
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int mx = 0;
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for (int i = 1; i <= n; i++) {
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if (dis[i] == INF) return -1;
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mx = max(mx, dis[i]);
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}
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return mx;
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}
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int main() {
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memset(h, -1, sizeof h);
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cin >> n >> m;
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while (m--) {
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int a, b, c;
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cin >> a >> b >> c;
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add(a, b, c), add(b, a, c);
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}
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printf("%d\n", dijkstra());
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return 0;
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}
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