Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Program to check whether we can take all courses or not in Python
Suppose we have a 2D matrix where matrix[i] represents the list of prerequisite courses needed to enroll course i. Now, we have to check whether it is possible to take all courses or not.
So, if the input is like matrix = [[1],[2],[]], then the output will be True, as we can take course 2, then course 1, and then course 0.
To solve this, we will follow these steps −
Define a function dfs(). This will take i
if vis[i] is true, then
return false
if chk[i] is true, then
return True
vis[i]:= True
for each j in matrix[i], do
if dfs(j) is false, then
return False
vis[i]:= False
chk[i]:= True
return True
From the main method, do the following −
vis:= a list of size same as row count of matrix and initially all are false
chk:= a list of size same as row count of matrix and initially all are false
for i in range 0 to row count of matrix, do
if dfs(i) is false, then
return False
return True
Let us see the following implementation to get better understanding −
Example
class Solution: def solve(self, matrix): vis=[False for _ in matrix] chk=[False for _ in matrix] def dfs(i): if vis[i]: return False if chk[i]: return True vis[i]=True for j in matrix[i]: if not dfs(j): return False vis[i]=False chk[i]=True return True for i in range(len(matrix)): if not dfs(i): return False return True ob = Solution() matrix = [ [1], [2], [] ] print(ob.solve(matrix))
Input
matrix = [ [1], [2], [] ]
Output
True
98 Views
