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OI-codes/LibreOJ/119/119.cpp

39 lines
944 B
C++

#include <bits/stdc++.h>
using namespace std;
int n, m, s, t, u, v, w, dist[2505];
vector<pair<int, int>> g[2505];
bool st[2505];
void dijkstra() {
memset(dist, 0x3f, sizeof(dist));
dist[s] = 0;
priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> q;
q.push(make_pair(0, s));
while (!q.empty()) {
auto t = q.top();
q.pop();
if (st[t.second]) continue;
for (auto i : g[t.second]) {
if (dist[i.first] > t.first + i.second) {
dist[i.first] = t.first + i.second;
q.push(make_pair(dist[i.first], i.first));
}
}
st[t.second] = true;
}
}
int main() {
cin >> n >> m >> s >> t;
for (int i = 1; i <= m; i++) {
cin >> u >> v >> w;
g[u].push_back(make_pair(v, w));
g[v].push_back(make_pair(u, w));
}
dijkstra();
cout << dist[t] << endl;
return 0;
}