P2984 [USACO10FEB]Chocolate Giving S

R53548464

Luogu/problem/P2984/P2984.cpp

@@ -0,0 +1,41 @@
+#include <bits/stdc++.h>
+
+using namespace std;
+
+int n, m, b, r, s, l, p, q, dist[50005];
+vector<pair<int, int>> g[50005];
+bool st[50005];
+
+void dijkstra() {
+    memset(dist, 0x3f, sizeof(dist));
+    priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> q;
+    dist[1] = 0;
+    q.push(make_pair(0, 1));
+    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 >> b;
+    for (int i = 1; i <= m; i++) {
+        cin >> r >> s >> l;
+        g[r].push_back(make_pair(s, l));
+        g[s].push_back(make_pair(r, l));
+    }
+    dijkstra();
+    for (int i = 1; i <= b; i++) {
+        cin >> p >> q;
+        cout << dist[p] + dist[q] << endl;
+    }
+    return 0;
+}