[BOJ] 특정한 최단 경로 / 골드 4 / 70분 실패 힌트사용

https://www.acmicpc.net/problem/1504

Author: YoonYn9915

YoonYn9915/dijkstra/2025-06-23-[백준]-#1504-특정한 최단 경로.py

@@ -0,0 +1,35 @@
+import sys
+import heapq
+
+input = sys.stdin.readline
+INF = float('inf')
+
+N, E = map(int, input().split())
+graph = [[] for _ in range(N + 1)]
+for _ in range(E):
+    a, b, c = map(int, input().split())
+    graph[a].append((b, c))
+    graph[b].append((a, c))
+v1, v2 = map(int, input().split())
+
+
+
+def dijkstra(start, end):
+    dist = [INF] * (N + 1)
+    dist[start] = 0
+    hq = [(0, start)]
+    while hq:
+        len, node = heapq.heappop(hq)
+        if len > dist[node]:
+            continue
+        for next_node, val in graph[node]:
+            if dist[next_node] > dist[node] + val:
+                dist[next_node] = dist[node] + val
+                heapq.heappush(hq, (dist[next_node], next_node))
+    return dist[end]
+
+
+path1 = dijkstra(1, v1) + dijkstra(v1, v2) + dijkstra(v2, N)
+path2 = dijkstra(1, v2) + dijkstra(v2, v1) + dijkstra(v1, N)
+
+print(-1) if path1 >= INF and path2 >= INF else print(min(path1, path2))