71-tgyuuAn

tgyuuAn/README.md

@@ -77,4 +77,5 @@
 | 68차시 | 2024.08.06 |  그리디  | <a href="https://www.acmicpc.net/problem/24337">가희와 탑</a> | https://github.com/AlgoLeadMe/AlgoLeadMe-1/pull/226
 | 69차시 | 2024.08.10 |  누적합, 수학  | <a href="https://www.acmicpc.net/problem/9527">1의 개수 세기</a> | https://github.com/AlgoLeadMe/AlgoLeadMe-1/pull/228
 | 70차시 | 2024.08.16 |  스택  | <a href="https://www.acmicpc.net/problem/22866">탑 보기</a> | https://github.com/AlgoLeadMe/AlgoLeadMe-1/pull/232
+| 71차시 | 2024.08.20 |  다익스트라  | <a href="https://www.acmicpc.net/problem/24042">다익스트라</a> | https://github.com/AlgoLeadMe/AlgoLeadMe-1/pull/235
 ---

tgyuuAn/다익스트라/횡단보도.py

@@ -0,0 +1,40 @@
+from collections import defaultdict
+from heapq import *
+import sys
+
+def input(): return sys.stdin.readline().rstrip()
+MAX = 100_000 * 700_000 + 1
+N, M = map(int, input().split())
+
+graph = defaultdict(lambda : defaultdict(list))
+
+for idx in range(1,M+1):
+    start, destination = map(int, input().split())
+    graph[start][destination].append(idx)
+    graph[destination][start].append(idx)
+
+costs = [MAX for _ in range(N+1)]
+visited = set()
+heap = [(0, 1)]
+while heap:
+    now_cost, now_idx = heappop(heap)
+
+    if now_idx in visited: continue
+    visited.add(now_idx)
+
+    if costs[now_idx] <= now_cost: continue
+    costs[now_idx] = now_cost
+
+    if now_idx == N: break
+
+    for neighbor in graph[now_idx]:
+        if neighbor in visited: continue
+
+        for neighbor_idx in graph[now_idx][neighbor]:
+
+            real_idx = now_cost % M
+            if real_idx < neighbor_idx:
+                heappush(heap, (neighbor_idx - real_idx + now_cost, neighbor))
+            else:
+                heappush(heap, (now_cost + M - real_idx + neighbor_idx, neighbor))
+print(costs[-1])