DEV Community

Cover image for 1971. Find if Path Exists in Graph
MD ARIFUL HAQUE
MD ARIFUL HAQUE

Posted on • Edited on

1

1971. Find if Path Exists in Graph

1971. Find if Path Exists in Graph

Easy

There is a bi-directional graph with n vertices, where each vertex is labeled from 0 to n - 1 (inclusive). The edges in the graph are represented as a 2D integer array edges, where each edges[i] = [ui, vi] denotes a bi-directional edge between vertex ui and vertex vi. Every vertex pair is connected by at most one edge, and no vertex has an edge to itself.

You want to determine if there is a valid path that exists from vertex source to vertex destination.

Given edges and the integers n, source, and destination, return true if there is a valid path from source to destination, or false otherwise.

Example 1:

  • Input: n = 3, edges = [[0,1],[1,2],[2,0]], source = 0, destination = 2
  • Output: true
  • Explanation: There are two paths from vertex 0 to vertex 2:
  • 0 → 1 → 2
  • 0 → 2

Example 2:

  • Input: n = 6, edges = [[0,1],[0,2],[3,5],[5,4],[4,3]], source = 0, destination = 5
  • Output: false
  • Explanation: There is no path from vertex 0 to vertex 5.

Constraints:

  • 1 <= n <= 2 * 105
  • 0 <= edges.length <= 2 * 105
  • edges[i].length == 2
  • 0 <= ui, vi <= n - 1
  • ui != vi
  • 0 <= source, destination <= n - 1
  • There are no duplicate edges.
  • There are no self edges.
class Solution {

    public $graph;

    /**
     * @param Integer $n
     * @param Integer[][] $edges
     * @param Integer $source
     * @param Integer $destination
     * @return Boolean
     */

    public function validPath(int $n, array $edges, int $source, int $destination): bool
    {
        $this->graph = array_fill(0, $n, 0);

        for ($i = 1; $i < $n; $i++) {
            $this->graph[$i] = $i;
        }

        foreach ($edges as $edge) {
            $this->merge($this->find($edge[0]), $this->find($edge[1]));
        }

        return $this->find($this->graph[$source]) == $this->find($this->graph[$destination]);
    }

    public function find($a) {
        return $this->graph[$a] == $a ? $a : $this->graph[$a] = $this->find($this->graph[$a]);
    }

    public function merge($a, $b): void
    {
        $this->graph[$a] = $b;
    }
}
Enter fullscreen mode Exit fullscreen mode

Contact Links

If you found this series helpful, please consider giving the repository a star on GitHub or sharing the post on your favorite social networks 😍. Your support would mean a lot to me!

Image of Docusign

Bring your solution into Docusign. Reach over 1.6M customers.

Docusign is now extensible. Overcome challenges with disconnected products and inaccessible data by bringing your solutions into Docusign and publishing to 1.6M customers in the App Center.

Learn more

Top comments (0)

A Workflow Copilot. Tailored to You.

Pieces.app image

Our desktop app, with its intelligent copilot, streamlines coding by generating snippets, extracting code from screenshots, and accelerating problem-solving.

Read the docs

Retry later