2024-06-03

tgyuuAn/README.md

@@ -63,4 +63,5 @@
 | 56차시 | 2023.05.18 |  BFS | <a href="https://www.acmicpc.net/problem/17836">공주님을 구해라!</a> | https://github.com/AlgoLeadMe/AlgoLeadMe-1/pull/193
 | 57차시 | 2023.05.26 |  분할 정복  | <a href="https://www.acmicpc.net/problem/2263">트리의 순회</a> | https://github.com/AlgoLeadMe/AlgoLeadMe-1/pull/197
 | 58차시 | 2023.05.30 |  백트래킹  | <a href="https://www.acmicpc.net/problem/1799">비숍</a> | https://github.com/AlgoLeadMe/AlgoLeadMe-1/pull/204
+| 59차시 | 2023.06.03 |  다익스트라 + 이분 탐색  | <a href="https://www.acmicpc.net/problem/14942">개미</a> | https://github.com/AlgoLeadMe/AlgoLeadMe-1/pull/207
 ---

tgyuuAn/다익스트라/개미.py

@@ -0,0 +1,85 @@
+from collections import defaultdict, deque
+from heapq import *
+import sys
+
+def input(): return sys.stdin.readline().rstrip()
+
+N = int(input())
+ant = [int(input()) for _ in range(N)]
+graph_info = defaultdict(lambda : defaultdict(int))
+neighbor_count = [0 for _ in range(N+1)]
+
+for _ in range(N-1):
+    start, destination, cost = map(int, input().split())
+    graph_info[start][destination] = cost
+    graph_info[destination][start] = cost
+
+    neighbor_count[start] += 1
+    neighbor_count[destination] += 1
+
+cost = [int(1e9) for _ in range(N+1)]
+heap = [(0,1)]
+parent = [0 for idx in range(N+1)]
+
+while heap:
+    now_cost, now_node = heappop(heap)
+
+    if now_cost >= cost[now_node] and now_node != 1: continue
+    cost[now_node] = now_cost
+
+    for next_node, next_cost in graph_info[now_node].items():
+        if now_cost + next_cost < cost[next_node]:
+            heappush(heap, (now_cost + next_cost, next_node))
+            parent[next_node] = now_node
+
+leaf_node = deque()
+for node, value in enumerate(neighbor_count):
+    if node in (0, 1): continue
+    if value == 1: leaf_node.append(node)
+
+#print(leaf_node)
+
+def check(mid, now_road, energy):
+    if now_road[0][1] - now_road[mid][1] <= energy: return True
+    return False
+
+answer = [0 for _ in range(N+1)]
+
+#print()
+#print(ant)
+for leaf in leaf_node:
+    now_node = leaf
+    now_road = deque()
+    while now_node != 0:
+        now_road.append((now_node, cost[now_node]))
+        now_node = parent[now_node]
+
+    while now_road:
+        now_idx, now_distance = now_road[0]
+        now_energy = ant[now_idx-1]
+
+        if answer[now_idx] != 0:
+            now_road.popleft()
+            continue
+
+       # print(now_road)
+
+        left = -1
+        right = len(now_road)
+        temp = 0
+        while left+1<right:
+            mid = (left+right)//2
+            #print(left, mid, right)
+
+            if check(mid, now_road, now_energy):
+                temp = mid
+                left = mid
+
+            else: right = mid
+
+        answer[now_idx] = now_road[temp][0]
+        #print(answer[1:])
+        #print()
+        now_road.popleft()
+
+for ans in answer[1:]: print(ans)