[최단경로] 1976435 황채원

13_최단 경로/필수/1238.cpp

@@ -0,0 +1,55 @@
+#include<iostream>
+#include<vector>
+#include<queue>
+#include<algorithm>
+#define MAX 1001
+#define INF 1e9
+using namespace std;
+
+int N, M, X;
+vector<pair<int, int>> graph[MAX];
+int dist[MAX];
+
+void dijkstra(int start) {
+    priority_queue<pair<int, int>> pq;
+    pq.push(make_pair(0, start));
+    dist[start] = 0;
+    while(!pq.empty()) {
+        int cost = -pq.top().first;
+        int here = pq.top().second;
+        pq.pop();
+        if(dist[here] < cost) continue;
+        for(int i=0; i<graph[here].size(); i++) {
+            int there = graph[here][i].first;
+            int nextDist = cost + graph[here][i].second;
+            if(dist[there] > nextDist) {
+                dist[there] = nextDist;
+                pq.push(make_pair(-nextDist, there));
+            }
+        }
+    }
+}
+
+int main() {
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL); cout.tie(NULL);
+
+    cin >> N >> M >> X;
+    for(int i=0; i<M; i++) {
+        int a, b, t;
+        cin >> a >> b >> t;
+        graph[a].push_back(make_pair(b, t));
+    }
+    int result = 0;
+    for(int i=1; i<=N; i++) {
+        fill(dist, dist+MAX, INF);
+        dijkstra(i);
+        int temp = dist[X];
+        fill(dist, dist+MAX, INF);
+        dijkstra(X);
+        temp += dist[i];
+        result = max(result, temp);
+    }
+    cout << result;
+    return 0;
+}