2024/9/3 Hot100 graph 拓扑排序 LeetCode之第100题

src/main/java/com/cool/hot100/graph/Num207.java

@@ -0,0 +1,51 @@
+package com.cool.hot100.graph;
+
+import java.util.*;
+
+/**
+ * Created with IntelliJ IDEA.
+ *
+ * @Author: Cool
+ * @Date: 2024/09/04/09:31
+ * DayNumber 1
+ * Hard 2
+ * Level ?
+ */
+public class Num207 {
+    List<List<Integer>> lists = new ArrayList<>();
+    int[] status;
+    boolean canFinis = true;
+
+    public boolean canFinish(int numCourses, int[][] prerequisites) {
+        status = new int[numCourses];
+        for (int i = 0; i < numCourses; i++) {
+            lists.add(new ArrayList<>());
+        }
+        for (int[] prerequisite : prerequisites) {
+            List<Integer> list = lists.get(prerequisite[0]);
+            list.add(prerequisite[1]);
+        }
+        for (int[] prerequisite : prerequisites) {
+            if (status[prerequisite[0]] == 0) {
+                dfs(prerequisite[0]);
+            }
+        }
+        return canFinis;
+    }
+
+    private void dfs(int index) {
+
+        List<Integer> list = lists.get(index);
+        for (Integer i : list) {
+            if (status[i] == 0) {
+                status[i] = 1;
+                dfs(i);
+                status[i] = 2;
+            } else if (status[i] == 1) {
+                canFinis = false;
+                return;
+            }
+        }
+    }
+
+}