This approach involves topologically sorting the courses based on their prerequisites and then calculating the minimal time to complete each course using dynamic programming.

• Create a directed graph where each course is a node, and a prerequisite relationship (a,b) is a directed edge from a to b.
• Perform a topological sort on the courses. This step ensures that all prerequisites of a course are considered before the course itself.
• Use dynamic programming to calculate the minimum time required to complete each course by iteratively adding its prerequisite's completion time.

This approach uses Depth-First Search (DFS) with memorization to efficiently compute the completion time for courses.

• Model the courses and prerequisites as a directed graph.
• Utilize DFS to explore courses, where each exploration path calculates the time required as we resolve prerequisites recursively.
• Utilize memorization to store already computed completion times, avoiding redundant calculations and ensuring optimal performance.