forked from varunu28/LeetCode-Java-Solutions
-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathCourse Schedule.java
More file actions
31 lines (27 loc) · 971 Bytes
/
Course Schedule.java
File metadata and controls
31 lines (27 loc) · 971 Bytes
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
class Solution {
Set<Integer> set = new HashSet<>();
public boolean canFinish(int numCourses, int[][] prerequisites) {
Map<Integer, Set<Integer>> map = new HashMap<>();
for (int[] prereq : prerequisites) {
map.computeIfAbsent(prereq[0], k -> new HashSet<>()).add(prereq[1]);
}
for (int i = 0; i < numCourses; i++) {
set.clear();
dfsHelper(map, i);
if (set.contains(i)) {
return false;
}
}
return true;
}
private void dfsHelper(Map<Integer, Set<Integer>> map, int courseNum) {
Iterator<Integer> iterator = map.getOrDefault(courseNum, new HashSet<>()).iterator();
while (iterator.hasNext()) {
int course = iterator.next();
if (!set.contains(course)) {
set.add(course);
dfsHelper(map, course);
}
}
}
}