44!

JYPARK/41to50/44.py

@@ -0,0 +1,37 @@
+import heapq
+from collections import defaultdict
+
+def solution(N, road, K):
+    answer = 0
+    visited = [False for _ in range(N)]
+    visited[0] = True
+    dist = {i+1: float("inf") for i in range(N)}
+    dist[1] = 0
+    q = []
+    graph = [[]for _ in range(N+1)]    
+
+    for current_node, adjacent_node, weight in road:
+        graph[current_node].append((adjacent_node, weight))
+        graph[adjacent_node].append((current_node, weight))
+
+    heapq.heappush(q, [1, 0])          #현재노드, 시작점에서 현재노드까지의 거리
+
+    while q:
+        current_node, weight = heapq.heappop(q)
+
+        if dist[current_node] < weight:
+            continue
+
+        for adjacent_node, new_weigth in graph[current_node]:                 #현재노드에 연결 돼있는 모든 노드를 볼 것임
+            if dist[adjacent_node] > dist[current_node] + new_weigth:
+                dist[adjacent_node] = dist[current_node] + new_weigth
+                heapq.heappush(q, [adjacent_node, dist[adjacent_node]])
+
+    for key in dist:
+        if dist[key] <= K:
+            answer += 1
+    return answer
+
+#N, road, K = 5, [[1,2,1],[2,3,3],[5,2,2],[1,4,2],[5,3,1],[5,4,2]], 3
+N, road, K = 6, [[1,2,1],[1,3,2],[2,3,2],[3,4,3],[3,5,2],[3,5,3],[5,6,1]], 4
+print(solution(N, road, K))