Package g2101_2200.s2192_all_ancestors_of_a_node_in_a_directed_acyclic_graph

Class Solution

java.lang.Object

g2101_2200.s2192_all_ancestors_of_a_node_in_a_directed_acyclic_graph.Solution

public class Solution
extends Object

2192 - All Ancestors of a Node in a Directed Acyclic Graph\. Medium You are given a positive integer `n` representing the number of nodes of a **Directed Acyclic Graph** (DAG). The nodes are numbered from `0` to `n - 1` ( **inclusive** ). You are also given a 2D integer array `edges`, where edges[i] = [fromi, toi] denotes that there is a **unidirectional** edge from fromi to toi in the graph. Return _a list_ `answer`_, where_ `answer[i]` _is the **list of ancestors** of the_ ith _node, sorted in **ascending order**_. A node `u` is an **ancestor** of another node `v` if `u` can reach `v` via a set of edges. **Example 1:**  **Input:** n = 8, edgeList = \[\[0,3],[0,4],[1,3],[2,4],[2,7],[3,5],[3,6],[3,7],[4,6]] **Output:** [ [],[],[],[0,1],[0,2],[0,1,3],[0,1,2,3,4],[0,1,2,3]] **Explanation:** The above diagram represents the input graph. - Nodes 0, 1, and 2 do not have any ancestors. - Node 3 has two ancestors 0 and 1. - Node 4 has two ancestors 0 and 2. - Node 5 has three ancestors 0, 1, and 3. - Node 6 has five ancestors 0, 1, 2, 3, and 4. - Node 7 has four ancestors 0, 1, 2, and 3. **Example 2:**  **Input:** n = 5, edgeList = \[\[0,1],[0,2],[0,3],[0,4],[1,2],[1,3],[1,4],[2,3],[2,4],[3,4]] **Output:** [ [],[0],[0,1],[0,1,2],[0,1,2,3]] **Explanation:** The above diagram represents the input graph. - Node 0 does not have any ancestor. - Node 1 has one ancestor 0. - Node 2 has two ancestors 0 and 1. - Node 3 has three ancestors 0, 1, and 2. - Node 4 has four ancestors 0, 1, 2, and 3. **Constraints:** * `1 <= n <= 1000` * `0 <= edges.length <= min(2000, n * (n - 1) / 2)` * `edges[i].length == 2` * 0 <= fromi, toi <= n - 1 * fromi != toi * There are no duplicate edges. * The graph is **directed** and **acyclic**.

Constructor Summary

Constructors

Constructor	Description
Solution()

Method Summary

Modifier and Type	Method	Description
List<List<Integer>>	getAncestors(int n, int[][] edges)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

Solution

public Solution()

Method Details

getAncestors

public List<List<Integer>> getAncestors(int n,
 int[][] edges)