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g1401_1500.s1462_course_schedule_iv.readme.md Maven / Gradle / Ivy

1462\. Course Schedule IV

Medium

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 ai first if you want to take course bi.

*   For example, the pair `[0, 1]` indicates that you have to take course `0` before you can take course `1`.

Prerequisites can also be **indirect**. If course `a` is a prerequisite of course `b`, and course `b` is a prerequisite of course `c`, then course `a` is a prerequisite of course `c`.

You are also given an array `queries` where queries[j] = [uj, vj]. For the jth query, you should answer whether course uj is a prerequisite of course vj or not.

Return _a boolean array_ `answer`_, where_ `answer[j]` _is the answer to the_ jth _query._

**Example 1:**

![](https://assets.leetcode.com/uploads/2021/05/01/courses4-1-graph.jpg)

**Input:** numCourses = 2, prerequisites = [[1,0]], queries = [[0,1],[1,0]]

**Output:** [false,true]

**Explanation:** The pair [1, 0] indicates that you have to take course 1 before you can take course 0. Course 0 is not a prerequisite of course 1, but the opposite is true.

**Example 2:**

**Input:** numCourses = 2, prerequisites = [], queries = [[1,0],[0,1]]

**Output:** [false,false]

**Explanation:** There are no prerequisites, and each course is independent.

**Example 3:**

![](https://assets.leetcode.com/uploads/2021/05/01/courses4-3-graph.jpg)

**Input:** numCourses = 3, prerequisites = [[1,2],[1,0],[2,0]], queries = [[1,0],[1,2]]

**Output:** [true,true]

**Constraints:**

*   `2 <= numCourses <= 100`
*   `0 <= prerequisites.length <= (numCourses * (numCourses - 1) / 2)`
*   `prerequisites[i].length == 2`
*   0 <= ai, bi <= n - 1
*   ai != bi
*   All the pairs [ai, bi] are **unique**.
*   The prerequisites graph has no cycles.
*   1 <= queries.length <= 104
*   0 <= ui, vi <= n - 1
*   ui != vi