From 759c9a46cb9ab718ea8b9f76a626254bc7e87fbe Mon Sep 17 00:00:00 2001
From: Shakthi Nandana <sgovind4@ncsu.edu>
Date: Mon, 4 May 2026 23:17:29 -0400
Subject: [PATCH] solution to problems

---
 course-schedule.py       | 48 ++++++++++++++++++++++++++++++++++++++++
 level-order-traversal.py | 41 ++++++++++++++++++++++++++++++++++
 2 files changed, 89 insertions(+)
 create mode 100644 course-schedule.py
 create mode 100644 level-order-traversal.py

diff --git a/course-schedule.py b/course-schedule.py
new file mode 100644
index 00000000..205f910d
--- /dev/null
+++ b/course-schedule.py
@@ -0,0 +1,48 @@
+# Time Complexity: O(V+E) V is the number of courses (vertices) and E is the number of prerequisites (edges)
+# Space Complexity: O(V+E)
+# Did this code successfully run on Leetcode : Yes
+
+
+from collections import defaultdict,deque
+class Solution(object):
+    def canFinish(self, numCourses, prerequisites):
+        """
+        :type numCourses: int
+        :type prerequisites: List[List[int]]
+        :rtype: bool
+        """
+        ndeg=[0]*numCourses
+        adjlist=defaultdict(list)
+        c=0
+        queue= deque()
+
+        for n in prerequisites:
+            ndeg[n[0]]+=1
+            adjlist[n[1]].append(n[0])
+
+        for i in range(numCourses):
+            if ndeg[i]==0:
+                c+=1
+                queue.append(i)
+
+        if c==numCourses: return True
+
+        while queue:
+            node = queue.popleft()
+
+            for neighbor in adjlist[node]:
+                ndeg[neighbor]-=1
+                if ndeg[neighbor]==0:
+                    queue.append(neighbor)
+                    c+=1
+                
+                if c==numCourses:
+                    return True
+        
+        return False
+        
+
+
+        
+
+        
\ No newline at end of file
diff --git a/level-order-traversal.py b/level-order-traversal.py
new file mode 100644
index 00000000..51e35e3c
--- /dev/null
+++ b/level-order-traversal.py
@@ -0,0 +1,41 @@
+# Time Complexity: O(n) 
+# Space Complexity: O(n)
+# Did this code successfully run on Leetcode : Yes
+
+from collections import deque
+# Definition for a binary tree node.
+class TreeNode(object):
+    def __init__(self, val=0, left=None, right=None):
+        self.val = val
+        self.left = left
+        self.right = right
+
+class Solution(object):
+    def levelOrder(self, root):
+        """
+        :type root: Optional[TreeNode]
+        :rtype: List[List[int]]
+        """
+        res=[]
+        level=0
+        if root==None:
+            return res
+        queue=deque([root])
+
+        while queue:
+            res.append([])
+            level_elements=len(queue)
+
+            for i in range(level_elements):
+                popped = queue.popleft()
+                res[level].append(popped.val)
+                if popped.left: 
+                    queue.append(popped.left)
+                if popped.right:
+                    queue.append(popped.right)
+            level+=1
+
+        return res
+
+
+        
\ No newline at end of file