Course scheduling-Coding question asked by Stanley Morgan, JPMC, Goldmann Sachs

Problem Statement:

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.

For example, the pair [0, 1], indicates that to take course 0 you have to first take course 1.

Return true if you can finish all courses. Otherwise, return false.

Input Format:

Integer and array depicting course to be taken and pre-requiste respectively

Output Format:

Boolean

Sample Input 1:

numCourses = 2, prerequisites = [[1,0]]

Sample Output 1:

True

Sample Input 2:

numCourses = 2, prerequisites = [[1,0],[0,1]]

Sample Output 2:

False

Constraint:

1 <= numCourses <= 20000 <= prerequisites.length <= 5000prerequisites[i].length == 20 <= ai, bi < numCourses

Approach:

  • Each element present in the prerequisite is treated as a node of a graph, as prerequisites[0] is dependent on prerequistes[1], a edge is directed from the latter to the former.
  • But in case if any two elements direct each other, a cycle is formed and we will not be able to chose the subject and complete it.
  • So if we find a cycle in the graph, our work is done.

Code:

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