Merge pull request #226 from hellomrsun/master

Add  Course Schedule II C#

Author: jinshendan

July-LeetCoding-Challenge/18-Course-Schedule-II/Course-Schedule-II.cs

@@ -0,0 +1,35 @@
+public class Solution {
+    public int[] FindOrder(int numCourses, int[][] prerequisites) {
+        if(numCourses == 0) return new int[0];
+        
+        var indegree = new int[numCourses];
+        for(int i=0; i<prerequisites.Length; i++){
+            indegree[prerequisites[i][0]]++;
+        }
+        
+        var order = new int[numCourses];
+        var index = 0;
+        Queue<int> queue = new Queue<int>();
+        for(int i=0; i<numCourses; i++){
+            if(indegree[i] == 0){
+                order[index++] = i;
+                queue.Enqueue(i);
+            }
+        }
+        
+        while(queue.Count > 0){
+            var prerequi = queue.Dequeue();
+            for(int i=0; i<prerequisites.Length; i++){
+                if(prerequisites[i][1] == prerequi){
+                    indegree[prerequisites[i][0]]--;
+                    if(indegree[prerequisites[i][0]] == 0){
+                        order[index++] = prerequisites[i][0];
+                        queue.Enqueue(prerequisites[i][0]);
+                    }    
+                }
+            }
+        }
+        
+        return (index == numCourses) ? order : new int[0];
+    }
+}

README.md

@@ -24,6 +24,8 @@ Solutions in various programming languages are provided. Enjoy it.
 15. [Reverse Words in a String](https://github.com/AlgoStudyGroup/Leetcode/tree/master/July-LeetCoding-Challenge/15-Reverse-Words-in-a-String): Pointer
 16. [Pow(x,n)](https://github.com/AlgoStudyGroup/Leetcode/tree/master/July-LeetCoding-Challenge/16-Pow(x,n)): Recursion
 17. [Top K Frequent Elements](https://github.com/AlgoStudyGroup/Leetcode/tree/master/July-LeetCoding-Challenge/17-Top-K-Frequent-Elements): Bucket
+18. [Course Schedule II](https://github.com/AlgoStudyGroup/Leetcode/tree/master/July-LeetCoding-Challenge/18-Course-Schedule-II): BFS
+
 
 ## June LeetCoding Challenge
 Click [here](https://leetcode.com/explore/challenge/card/june-leetcoding-challenge/) for problem descriptions.