寻找图中是否存在路径

/*
 * Problem: Given a bidirectional graph represented by an integer n (number of vertices) and an array of edges,
 * determine if there exists a valid path from source to destination.
 *
 * Approach: We can solve this problem using Breadth First Search (BFS) with Java Streams.
 * We will use an adjacency list to represent the graph and a boolean array to mark visited nodes.
 * Start from the source node, traverse the graph using BFS, and check if we can reach the destination node.
 */

import java.util.*;
import java.util.stream.Collectors;

public class SolutionStream {
    public boolean validPath(int n, int[][] edges, int source, int destination) {
        // Create adjacency list
        Map<Integer, List<Integer>> graph = Arrays.stream(edges)
            .collect(Collectors.groupingBy(
                edge -> edge[0],
                Collectors.mapping(edge -> edge[1], Collectors.toList())
            ));
        Arrays.stream(edges).forEach(edge -> graph.computeIfAbsent(edge[1], k -> new ArrayList<>()).add(edge[0]));

        // Queue for BFS
        Queue<Integer> queue = new LinkedList<>();
        queue.offer(source);

        // Array to track visited nodes
        boolean[] visited = new boolean[n];
        visited[source] = true;

        // BFS traversal
        while (!queue.isEmpty()) {
            int node = queue.poll();
            if (node == destination) return true;
            for (int neighbor : graph.getOrDefault(node, Collections.emptyList())) {
                if (!visited[neighbor]) {
                    visited[neighbor] = true;
                    queue.offer(neighbor);
                }
            }
        }

        return false;
    }
}