feat: course-schedule

Author: minji-go

course-schedule/minji-go.java

@@ -0,0 +1,45 @@
+/**
+ * <a href="https://leetcode.com/problems/course-schedule/">week10-3. course-schedule   </a>
+ * <li>Description: Return true if you can finish all courses. Otherwise, return false  </li>
+ * <li>Topics: Depth-First Search, Breadth-First Search, Graph, Topological Sort        </li>
+ * <li>Time Complexity: O(N+E), Runtime 7ms        </li>
+ * <li>Space Complexity: O(N+E), Memory 45.68MB    </li>
+ * <li>Note : refer to the answer. remember the topic of topological sort </li>
+ */
+class Solution {
+    public boolean canFinish(int numCourses, int[][] prerequisites) {
+        int[] inDegree = new int[numCourses];
+        List<List<Integer>> graph = new ArrayList<>();
+        for (int i=0; i<numCourses; i++){
+            graph.add(new ArrayList<>());
+        }
+
+        for(int[] pre : prerequisites) {
+            int dest = pre[0], src = pre[1];
+            graph.get(src).add(dest);
+            inDegree[dest]++;
+        }
+
+        Queue<Integer> queue = new LinkedList<>();
+        for (int i=0; i<numCourses; i++) {
+            if(inDegree[i] == 0) {
+                queue.offer(i);
+            }
+        }
+
+        int count = 0;
+        while(!queue.isEmpty()){
+            int node = queue.poll();
+            count++;
+
+            for(int neighbor : graph.get(node)) {
+                inDegree[neighbor]--;
+                if(inDegree[neighbor] == 0) {
+                    queue.offer(neighbor);
+                }
+            }
+        }
+
+        return count == numCourses;
+    }
+}