Create Day29.cpp

Author: starwiz-7

Day29.cpp

@@ -0,0 +1,40 @@
+/*
+    Author: Aryan Yadav
+    Course Schedule
+    Algorithm: Graphs
+    Difficulty: Medium
+*/
+
+class Solution {
+public:
+    bool canFinish(int numCourses, vector<vector<int>>& prerequisites) {
+        queue<int> zeroInDegree;
+        unordered_map<int, unordered_set<int>> inDegree;
+        unordered_map<int, unordered_set<int>> outDegree;
+        for (int i = 0; i < prerequisites.size(); ++i) {
+            inDegree[prerequisites[i][0]].insert(prerequisites[i][1]);
+            outDegree[prerequisites[i][1]].insert(prerequisites[i][0]);
+        }
+        for(int i = 0; i < numCourses; ++i) {
+            if(inDegree.find(i) == inDegree.end()) {
+                zeroInDegree.push(i);
+            }
+        }
+        while(!zeroInDegree.empty()) {
+            int prerequisite = zeroInDegree.front();
+            zeroInDegree.pop();
+            for (const auto & course: outDegree[prerequisite]) {
+                inDegree[course].erase(prerequisite);
+                if (inDegree[course].empty()) {
+                    zeroInDegree.push(course);
+                }
+            }
+            outDegree.erase(prerequisite);
+        }
+        if (!outDegree.empty()) {
+            return false;
+        }
+        
+        return true;
+    }
+};