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OI-codes/S2OJ/106/106.cpp

42 lines
1015 B
C++

#pragma GCC optimize("Ofast")
#include <bits/stdc++.h>
using namespace std;
int n, m, s, t, u, v, w, dist[2505];
vector<pair<int, int>> g[2505];
bool vis[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 (vis[t.second]) continue;
for (auto i : g[t.second]) {
if (dist[i.first] > i.second + t.first) {
dist[i.first] = i.second + t.first;
q.push(make_pair(dist[i.first], i.first));
}
}
vis[t.second] = true;
}
}
int main() {
std::ios::sync_with_stdio(false);
cin >> n >> m >> s >> t;
for (int i = 0; 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;
}