2024-07-16 22:54:21

Affected files:
.obsidian/workspace.json
src/content/blog/leet-code-207-course-schedule.md

.obsidian/workspace.json

@@ -4,16 +4,16 @@
     "type": "split",
     "children": [
       {
-        "id": "5c7cbcec3c13656e",
+        "id": "c93cbacdb763ad00",
         "type": "tabs",
         "children": [
           {
-            "id": "bb9e313e9ec35bc3",
+            "id": "4077864ed2ae2ddd",
             "type": "leaf",
             "state": {
               "type": "markdown",
               "state": {
-                "file": "src/content/blog/leet-code-74-search-a-2d-matrix.md",
+                "file": "src/content/blog/leet-code-919-complete-binary tree-inserter.md",
                 "mode": "source",
                 "source": false
               }
@@ -22,16 +22,16 @@
         ]
       },
       {
-        "id": "c93cbacdb763ad00",
+        "id": "67b79f11d4a32e93",
         "type": "tabs",
         "children": [
           {
-            "id": "4077864ed2ae2ddd",
+            "id": "d3c142ad93a1e3ac",
             "type": "leaf",
             "state": {
               "type": "markdown",
               "state": {
-                "file": "src/content/blog/leet-code-919-complete-binary tree-inserter.md",
+                "file": "src/content/blog/leet-code-207-course-schedule.md",
                 "mode": "source",
                 "source": false
               }
@@ -103,7 +103,7 @@
             "state": {
               "type": "backlink",
               "state": {
-                "file": "src/content/blog/leet-code-919-complete-binary tree-inserter.md",
+                "file": "src/content/blog/leet-code-207-course-schedule.md",
                 "collapseAll": false,
                 "extraContext": false,
                 "sortOrder": "alphabetical",
@@ -120,7 +120,7 @@
             "state": {
               "type": "outgoing-link",
               "state": {
-                "file": "src/content/blog/leet-code-919-complete-binary tree-inserter.md",
+                "file": "src/content/blog/leet-code-207-course-schedule.md",
                 "linksCollapsed": false,
                 "unlinkedCollapsed": true
               }
@@ -143,7 +143,7 @@
             "state": {
               "type": "outline",
               "state": {
-                "file": "src/content/blog/leet-code-919-complete-binary tree-inserter.md"
+                "file": "src/content/blog/leet-code-207-course-schedule.md"
               }
             }
           }
@@ -166,11 +166,12 @@
       "table-editor-obsidian:Advanced Tables Toolbar": false
     }
   },
-  "active": "4077864ed2ae2ddd",
+  "active": "d3c142ad93a1e3ac",
   "lastOpenFiles": [
+    "src/content/blog/leet-code-919-complete-binary tree-inserter.md",
+    "src/content/blog/leet-code-207-course-schedule.md",
     "src/content/blog/leet-code-74-search-a-2d-matrix.md",
     "src/content/blog/boj-2529-부등호.md",
-    "src/content/blog/leet-code-919-complete-binary tree-inserter.md",
     "src/content/blog/boj-1339-단어-수학.md",
     "src/content/blog/boj-2660-회장뽑기.md",
     "src/content/blog/boj-2011-암호코드.md",
@@ -195,7 +196,6 @@
     "dist/posts/aqua를-이용해-wsl-ubuntu에-neovim을-설치하자.png",
     "src/content/blog/manage-cli-program-version-using-aqua-proj-on-windows.md",
     "src/content/blog/astro-paper-4.md",
-    "src/content/blog/implementing-a-worker-thread-pool-in-c.md",
     "dist/assets/[email protected]",
     "dist/assets/forrest-gump-quote.webp.jpg",
     "dist/_astro/[email protected]",

src/content/blog/leet-code-207-course-schedule.md

@@ -0,0 +1,87 @@
+---
+author: Gyunseo Lee
+title: "LeetCode 207: Course Schedule"
+pubDatetime: 2024-07-16T22:37:00+09:00
+modDatetime: 2024-07-16T22:37:00+09:00
+featured: false
+draft: false
+tags:
+  - PS
+  - Algorithms
+  - DAG
+  - Topological-Sort
+  - BFS
+  - DFS
+  - LeetCode
+  - Cycle
+  - Kahn
+  - Kosaraju
+description: "\b이 문제는 푸는 방법이 엄청 많네요 ㅎㅎ"
+ogImage: ""
+---
+
+## Table of contents
+
+## 들어가며
+
+걸린 시간: 3시간 (50분 안에 못 풀고 cycle 판정에 대해 찾아봤습니다...)
+
+## 접근
+
+WIP
+
+## 구현
+
+WIP
+
+### DFS + 3 state (from CLRS)
+
+```python
+class Solution:
+    def get_adjacency_list(self, n, edge_lists):
+        adj_list = [[] for _ in range(n)]
+
+        for dst, src in edge_lists:
+            adj_list[src].append(dst)
+
+        return adj_list
+
+    def canFinish(self, numCourses: int, prerequisites: List[List[int]]) -> bool:
+        adj_list = self.get_adjacency_list(numCourses, prerequisites)
+
+        # 0: not visited yet, -1: now being processed, 1: had been processed
+        node_state_list = [0 for _ in range(numCourses)]
+
+        # check cycle
+        def DFS(cur_node):
+
+            for next_node in adj_list[cur_node]:
+                if node_state_list[next_node] == 1:
+                    continue
+
+                if node_state_list[next_node] == -1:
+                    return True
+
+                node_state_list[next_node] = -1
+                if DFS(next_node):
+                    node_state_list[cur_node] = 1
+                    return True
+
+            node_state_list[cur_node] = 1
+            return False
+
+        for i in range(numCourses):
+            if node_state_list[i] == 1:
+                continue
+
+            node_state_list[i] = -1
+            if DFS(i):
+                return False
+
+        return True
+
+```
+
+### Khan 알고리즘 (위상 정렬)
+
+### Kosaraju 알고리즘 (SCC)