Update network-delay-time.cpp

Author: kamyu104

C++/network-delay-time.cpp

@@ -15,17 +15,26 @@ class Solution {
 
         int result = 0;
         unordered_set<int> lookup;
+        unordered_map<int, int> best;
         priority_queue<P, vector<P>, greater<P>> min_heap;
         min_heap.emplace(0, K - 1);
         while (!min_heap.empty() && lookup.size() != N) {
             int u;
             tie(result, u) = min_heap.top(); min_heap.pop();
             lookup.emplace(u);
+            if (best.count(u) &&
+                best[u] < result) {
+                continue;
+            }
             for (const auto& kvp : adj[u]) {
                 int v, w;
                 tie(v, w) = kvp;
                 if (lookup.count(v)) continue;
-                min_heap.emplace(result + w, v);
+                if (!best.count(v) ||
+                    result + w < best[v]) {
+                    best[v] = result + w;
+                    min_heap.emplace(result + w, v);
+                }
             }
         }
         return lookup.size() == N ? result : -1;