Tutorialspoint
Problem
Solution
Submissions
Back

Course Schedule

Certification: Intermediate Level Accuracy: 0% Submissions: 0 Points: 10

Write a JavaScript program to determine if it's possible to finish all courses given prerequisites. There are a total of numCourses courses you have to take, labeled from 0 to numCourses - 1. You are given an array prerequisites where prerequisites[i] = [ai, bi] indicates that you must take course bi first if you want to take course ai. This is essentially detecting if there's a cycle in a directed graph.

Example 1
    
      
  • Input: numCourses = 2, prerequisites = [[1,0]]
    • 
      
  • Output: true
    • 
      
  • Explanation: 
    • There are 2 courses to take (0 and 1). 
    • To take course 1, you must first take course 0. 
    • Course 0 has no prerequisites. 
    • Therefore, it's possible to complete all courses: 0 → 1.
    •
Example 2
    
      
  • Input: numCourses = 2, prerequisites = [[1,0],[0,1]]
    • 
      
  • Output: false
    • 
      
  • Explanation: 
    • There are 2 courses to take (0 and 1). 
    • To take course 1, you must first take course 0. 
    • To take course 0, you must first take course 1. 
    • This creates a circular dependency (cycle). 
    • Therefore, it's impossible to complete all courses.
    •
Constraints
    
      
  • 1 ≤ numCourses ≤ 2000
    • 
      
  • 0 ≤ prerequisites.length ≤ 5000
    • 
      
  • prerequisites[i].length == 2
    • 
      
  • 0 ≤ ai, bi < numCourses
    • 
      
  • All the pairs prerequisites[i] are unique
    • 
      
  • Time Complexity: O(V + E)
    • 
      
  • Space Complexity: O(V + E)
    •
ArraysAlgorithmsMicrosoftWipro
Editorial

Login to view the detailed solution and explanation for this problem.

My Submissions
All Solutions
Refresh
Lang Status Date Code
You do not have any submissions for this problem.
Refresh
User Lang Status Date Code
No submissions found.

Please Login to continue
Solve Problems

 
 
 
Output Window
Clear All Apply Filters

Trending

Others

SIGN IN

Don't have an account? Register

Hint
Solution

Solution Hints

    
      
  • Build an adjacency list representation of the directed graph from prerequisites
    • 
      
  • Use DFS (Depth First Search) to detect cycles in the graph
    • 
      
  • Maintain a visited array with three states: unvisited, visiting, and visited
    • 
      
  • If during DFS you encounter a node that is currently being visited, there's a cycle
    • 
      
  • Use topological sorting approach or cycle detection to solve the problem
    • 
      
  • Return false if any cycle is detected, true otherwise
    •

Steps to solve by this approach:

 Step 1: Build an adjacency list representation of the directed graph from the prerequisites array.

 Step 2: Initialize a state array to track the status of each node (unvisited, visiting, visited).

 Step 3: Create a DFS helper function that detects cycles by checking if a node is currently being visited.

 Step 4: For each unvisited course, perform DFS to check for cycles in its dependency chain.

 Step 5: If any cycle is detected during DFS traversal, return false immediately.

 Step 6: Mark nodes as visiting when entering DFS and visited when leaving to track the recursion path.

 Step 7: If no cycles are found after checking all courses, return true indicating all courses can be finished.

Submitted Code :