add cpp solution

jinshendan · jinshendan · commit 11907ccefc0b · 2020-05-29T14:05:26.000+02:00
diff --git a/May-LeetCoding-Challenge/29-Course-Schedule/Course-Schedule.cpp b/May-LeetCoding-Challenge/29-Course-Schedule/Course-Schedule.cpp
@@ -0,0 +1,28 @@
+class Solution {
+public:
+   
+    bool canFinish(int numCourses, vector<vector<int>>& prerequisites) {
+        vector<int> deg(numCourses, 0);
+        vector<vector<int>> G(numCourses, vector<int>());
+        for (int i = 0; i < prerequisites.size(); i ++){
+            deg[prerequisites[i][0]]++;
+            G[prerequisites[i][1]].push_back(prerequisites[i][0]);
+        }
+        
+        queue<int> q;
+        for (int i = 0; i < numCourses; i++)  if (!deg[i]) q.push(i);
+        int sum = 0;
+        while(!q.empty()){
+            int i = q.front(); 
+            q.pop();
+            sum ++;
+            for (auto j: G[i]){
+                deg[j]--;
+                if (!deg[j]) q.push(j);
+            }
+        }
+        
+        return sum == numCourses;
+        
+    }
+};
