Question Link : https://leetcode.com/problems/minimum-number-of-vertices-to-reach-all-nodes/

Difficulty: Medium

Premium: False

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Given a directed acyclic graph, with n vertices numbered from 0 to n-1, and an array edges where edges[i] = [fromi, toi] represents a directed edge from node fromi to node toi. Find the smallest set of vertices …

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Question Link : https://leetcode.com/problems/course-schedule/

Difficulty: Medium

Premium: False

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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 …

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Question Link : https://leetcode.com/problems/alien-dictionary/

Difficulty: Hard

Premium: True

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There is a new alien language that uses the English alphabet. However, the order of the letters is unknown to you. You are given a list of strings words from the alien language's dictionary. Now it is claimed …

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Question Link : https://leetcode.com/problems/verifying-an-alien-dictionary/

Difficulty: Easy

Premium: False

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In an alien language, surprisingly, they also use English lowercase letters, but possibly in a different order. The order of the alphabet is some permutation of lowercase letters. Given a sequence of words written in the alien language …

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