2024-07-07 20:33:05

Affected files:
.obsidian/workspace.json
src/content/blog/boj-2660-회장뽑기.md

.obsidian/workspace.json

@@ -4,34 +4,16 @@
     "type": "split",
     "children": [
       {
-        "id": "0fb89b2a6940e666",
+        "id": "ea8dbc547ef84373",
         "type": "tabs",
         "children": [
           {
-            "id": "d150f0dbbe8f52e7",
+            "id": "443ea8f1c7a755e2",
             "type": "leaf",
             "state": {
               "type": "markdown",
               "state": {
-                "file": "src/content/blog/leet-code-1438-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit.md",
-                "mode": "source",
-                "source": false
-              }
-            }
-          }
-        ]
-      },
-      {
-        "id": "932958f597546de7",
-        "type": "tabs",
-        "children": [
-          {
-            "id": "a847079fc4a2b861",
-            "type": "leaf",
-            "state": {
-              "type": "markdown",
-              "state": {
-                "file": "src/content/blog/boj-1309-동물원.md",
+                "file": "src/content/blog/boj-2660-회장뽑기.md",
                 "mode": "source",
                 "source": false
               }
@@ -103,7 +85,7 @@
             "state": {
               "type": "backlink",
               "state": {
-                "file": "src/content/blog/boj-1309-동물원.md",
+                "file": "src/content/blog/boj-2660-회장뽑기.md",
                 "collapseAll": false,
                 "extraContext": false,
                 "sortOrder": "alphabetical",
@@ -120,7 +102,7 @@
             "state": {
               "type": "outgoing-link",
               "state": {
-                "file": "src/content/blog/boj-1309-동물원.md",
+                "file": "src/content/blog/boj-2660-회장뽑기.md",
                 "linksCollapsed": false,
                 "unlinkedCollapsed": true
               }
@@ -143,7 +125,7 @@
             "state": {
               "type": "outline",
               "state": {
-                "file": "src/content/blog/boj-1309-동물원.md"
+                "file": "src/content/blog/boj-2660-회장뽑기.md"
               }
             }
           }
@@ -166,10 +148,11 @@
       "table-editor-obsidian:Advanced Tables Toolbar": false
     }
   },
-  "active": "a847079fc4a2b861",
+  "active": "443ea8f1c7a755e2",
   "lastOpenFiles": [
-    "src/content/blog/leet-code-1438-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit.md",
     "src/content/blog/boj-1309-동물원.md",
+    "src/content/blog/boj-2660-회장뽑기.md",
+    "src/content/blog/leet-code-1438-longest-continuous-subarray-with-absolute-diff-less-than-or-equal-to-limit.md",
     "src/content/blog/leet-code-438-find-all-anagrams-in-a-string.md",
     "src/content/blog/boj-10159-저울.md",
     "src/content/blog/leet-code-64-minimum-path-sum.md",
@@ -212,7 +195,6 @@
     "src/content/blog/boj-15666-N과-M-(12).md",
     "src/content/blog/boj-15664-N과-M-(10).md",
     "src/content/blog/boj-15663-N과-M-(9).md",
-    "src/content/blog/boj-11728-배열-합치기.md",
-    "src/content/blog/boj-10819-차이를-최대로.md"
+    "src/content/blog/boj-11728-배열-합치기.md"
   ]
 }

src/content/blog/boj-2660-회장뽑기.md

@@ -0,0 +1,81 @@
+---
+author: Gyunseo Lee
+title: "BOJ 백준 2660: 회장뽑기"
+pubDatetime: 2024-07-07T19:00:00+09:00
+modDatetime: 2024-07-07T19:00:00+09:00
+featured: false
+draft: false
+tags:
+  - PS
+  - BOJ
+  - Algorithms
+  - BFS
+  - 실랜디
+  - 골랜디
+description: 항상 문제를 읽고 종이와 펜으로 먼저 풀어 보자...
+ogImage: ""
+---
+
+## Table of contents
+
+## 들어가며
+
+걸린 시간: 24분
+
+사실 처음에 문제를 읽었을 때 무슨 말인지 잘 이해가 안 갔습니다.  
+그럴 때에는 억지로 문제를 이해하려 들지 말고, 주어진 input값을 직접 simulation하면 잘 이해가 되는 거 같더라고요.
+
+## 접근
+
+![](https://res.cloudinary.com/gyunseo-blog/image/upload/f_auto/v1720351765/image_gyfx0g.png)
+
+결국 문제의 핵심은 그래프 탐색을 몇 번만에 다 할 수 있냐를 각 노드마다 시작점으로 줘서 구하는 것이었어요.  
+다행히 N은 최대 50이어서, 어렵지 않게 모든 노드에 대해 각각 1번씩 BFS를 해주어서 쉽게 답을 구해낼 수 있었답니다.
+
+## 구현
+
+```python
+import sys
+input = sys.stdin.readline
+from collections import deque
+
+def BFS(start):
+    distance[start] = 1
+    q = deque()
+    q.append(start)
+
+    while q:
+        cur_node = q.popleft()
+        for next_node in graph[cur_node]:
+            if distance[next_node] > 0:
+                continue
+            distance[next_node] = distance[cur_node] + 1
+            q.append(next_node)
+
+
+if __name__ == "__main__":
+    N = int(input().strip())
+    graph = [[] for _ in range(N + 1)]
+    distance = [0 for _ in range(N + 1)]
+    ansList = []
+    minStepsToTraverseAllNodes = int(1e9)
+    while True:
+        u, v = map(int, input().strip().split())
+        if u == -1 and v == -1:
+            break
+        graph[u].append(v)
+        graph[v].append(u)
+    for start_node in range(1, N + 1):
+        BFS(start_node)
+        stepsToTraverseAllNodes = max(distance) - 1
+        minStepsToTraverseAllNodes = min(minStepsToTraverseAllNodes, stepsToTraverseAllNodes)
+        ansList.append((start_node, stepsToTraverseAllNodes))
+        distance = [0 for _ in range(N + 1)]
+
+    ansList = [*map(lambda x: x[0], filter(lambda x: x[1] == minStepsToTraverseAllNodes, ansList))]
+    print(minStepsToTraverseAllNodes, len(ansList))
+    print(" ".join(map(str, ansList)))
+    # N이 0, 1일 때는 처리를 안 해줘도 되나..?
+```
+
+filter, map 함수를 적극 이용해 봤습니다. (코드를 줄이기 위해서...?!)