횡단보도 풀이

Author: saebyeok0306

BAEKJOON/3Gold/횡단보도.py

@@ -0,0 +1,53 @@
+# 
+# https://www.acmicpc.net/problem/24042
+
+"""
+4 5
+1 2
+3 4
+1 3
+4 1
+2 3
+"""
+
+input = __import__("sys").stdin.readline
+
+N,M = map(int, input().split())
+graph = [[] for _ in range(N+1)]
+for i in range(M):
+    a,b = map(int, input().split())
+    graph[a].append((b,i))
+    graph[b].append((a,i))
+
+INF = int(1e11)
+
+def dijkstra():
+    import heapq
+
+    dist = [INF]*(N+1)
+    heap = [(0, 1)]
+    dist[1] = 0
+
+    while heap:
+        cost, node = heapq.heappop(heap)
+
+        if dist[node] < cost:
+            continue
+
+        timing = cost % M
+        for nxt_node, nxt_timing in graph[node]:
+            nxt_cost = dist[node]+1
+            if nxt_timing >= timing:
+                nxt_cost += nxt_timing-timing
+            else:
+                nxt_cost += M+nxt_timing-timing
+
+            if nxt_cost >= dist[nxt_node]:
+                continue
+            
+            dist[nxt_node] = nxt_cost
+            heapq.heappush(heap, (nxt_cost, nxt_node))
+
+    print(dist[N])
+
+dijkstra()