Package g0201_0300.s0210_course_schedule_ii

Class Solution

  • All Implemented Interfaces:
    
public final class Solution

    210 - Course Schedule II\.

    Medium

    There are a total of numCourses courses you have to take, labeled from 0 to numCourses - 1. You are given an array prerequisites where <code>prerequisitesi = a<sub>i</sub>, b<sub>i</sub></code> indicates that you must take course <code>b<sub>i</sub></code> first if you want to take course <code>a<sub>i</sub></code>.

    • For example, the pair [0, 1], indicates that to take course 0 you have to first take course 1.

    Return the ordering of courses you should take to finish all courses. If there are many valid answers, return any of them. If it is impossible to finish all courses, return an empty array.

    Example 1:

    Input: numCourses = 2, prerequisites = \[\[1,0]]

    Output: 0,1

    Explanation: There are a total of 2 courses to take. To take course 1 you should have finished course 0. So the correct course order is 0,1.

    Example 2:

    Input: numCourses = 4, prerequisites = \[\[1,0],2,0,3,1,3,2]

    Output: 0,2,1,3

    Explanation: There are a total of 4 courses to take. To take course 3 you should have finished both courses 1 and 2. Both courses 1 and 2 should be taken after you finished course 0. So one correct course order is 0,1,2,3. Another correct ordering is 0,2,1,3.

    Example 3:

    Input: numCourses = 1, prerequisites = []

    Output: 0

    Constraints:

    • 1 &lt;= numCourses &lt;= 2000

    • 0 &lt;= prerequisites.length &lt;= numCourses * (numCourses - 1)

    • prerequisites[i].length == 2

    • <code>0 <= a<sub>i</sub>, b<sub>i</sub>< numCourses</code>

    • <code>a<sub>i</sub> != b<sub>i</sub></code>

    • All the pairs <code>a<sub>i</sub>, b<sub>i</sub></code> are distinct.

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description

    • Field Summary

      Fields 
      Modifier and Type Field Description

    • Constructor Summary

      Constructors 
      Constructor Description
      Solution()

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description

    • Method Summary

      Modifier and Type Method Description
      final IntArray findOrder(Integer numCourses, Array<IntArray> prerequisites)

      • Methods inherited from class java.lang.Object

        clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait