Package g0201_0300.s0210_course_schedule_ii

Class Solution

java.lang.Object
g0201_0300.s0210_course_schedule_ii.Solution
public class Solution extends Object
210 - Course Schedule II.<p>Medium</p> <p>There are a total of <code>numCourses</code> courses you have to take, labeled from <code>0</code> to <code>numCourses - 1</code>. You are given an array <code>prerequisites</code> where <code>prerequisites[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> indicates that you <strong>must</strong> take course <code>b<sub>i</sub></code> first if you want to take course <code>a<sub>i</sub></code>.</p> <ul> <li>For example, the pair <code>[0, 1]</code>, indicates that to take course <code>0</code> you have to first take course <code>1</code>.</li> </ul> <p>Return <em>the ordering of courses you should take to finish all courses</em>. If there are many valid answers, return <strong>any</strong> of them. If it is impossible to finish all courses, return <strong>an empty array</strong>.</p> <p><strong>Example 1:</strong></p> <p><strong>Input:</strong> numCourses = 2, prerequisites = [[1,0]]</p> <p><strong>Output:</strong> [0,1]</p> <p><strong>Explanation:</strong></p> <pre><code> 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]. </code></pre> <p><strong>Example 2:</strong></p> <p><strong>Input:</strong> numCourses = 4, prerequisites = [[1,0],[2,0],[3,1],[3,2]]</p> <p><strong>Output:</strong> [0,2,1,3]</p> <p><strong>Explanation:</strong></p> <pre><code> 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]. </code></pre> <p><strong>Example 3:</strong></p> <p><strong>Input:</strong> numCourses = 1, prerequisites = []</p> <p><strong>Output:</strong> [0]</p> <p><strong>Constraints:</strong></p> <ul> <li><code>1 <= numCourses <= 2000</code></li> <li><code>0 <= prerequisites.length <= numCourses * (numCourses - 1)</code></li> <li><code>prerequisites[i].length == 2</code></li> <li><code>0 <= a<sub>i</sub>, b<sub>i</sub> < numCourses</code></li> <li><code>a<sub>i</sub> != b<sub>i</sub></code></li> <li>All the pairs <code>[a<sub>i</sub>, b<sub>i</sub>]</code> are <strong>distinct</strong>.</li> </ul>

  • Constructor Details

    • Solution

      public Solution()

  • Method Details

    • findOrder

      public int[] findOrder(int numCourses, int[][] prerequisites)