[BOJ] 1865 웜홀 (G3)

Author: uiop5809

박예진/2주차/260106.cpp

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+//https://www.acmicpc.net/problem/1865
+#include <iostream>
+#include <algorithm>
+#include <vector>
+#include <cstring>
+
+using namespace std;
+
+/*
+    벨만포드 O(VE) 
+    1. V - 1개만큼 모든 노드 간선 순회
+    2. V에도 줄어들면 음수 사이클 존재
+ */
+
+struct Edge {
+    int n, cost;
+};
+
+int N, M, W;
+const long long INF = 1e12;
+
+vector<long long> dist;
+vector<vector<Edge>> graph;
+
+bool bellmanford(){
+    dist.assign(N + 1, INF);
+
+    for(int k = 1; k <= N; k++){
+        for(int i = 1; i <= N; i++){
+            for(int j = 0; j < graph[i].size(); j++){
+                int next = graph[i][j].n;
+                int nextcost = graph[i][j].cost;
+
+                if (dist[next] > dist[i] + nextcost) {
+                    dist[next] = dist[i] + nextcost;
+                    // N번째에도 값이 변경되면 음수 사이클 존재
+                    if (k == N) return true;
+                }
+            }
+        }
+    }
+    return false; 
+}
+
+int main(){
+    ios_base::sync_with_stdio(false);
+    cin.tie(NULL); cout.tie(NULL);
+
+    int TC;
+    cin >> TC;
+    while(TC--) {
+        cin >> N >> M >> W;
+        int S, E, T;
+        graph.resize(N + 1);
+        for(int i = 0; i < M; i++){ // 무방향
+            cin >> S >> E >> T;
+            graph[S].push_back({E, T});
+            graph[E].push_back({S, T});
+        }
+        for(int i = 0; i < W; i++){ // 방향
+            cin >> S >> E >> T;
+            graph[S].push_back({E, -T});
+        }
+        
+        if (bellmanford()) cout << "YES\n";
+        else cout << "NO\n";
+        graph.clear();
+    }
+}