How should I practice Shortest Path in an Unweighted Graph?

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Shortest Path in an Unweighted Graph

Citadel● EasyFULLTIMEOA

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Problem statement

You are given an undirected, unweighted graph with n vertices numbered from 0 through n - 1. Each pair edges[i] = [u, v] represents an edge connecting vertices u and v.

Given vertices source and target, return the minimum number of edges on any path from source to target. Return -1 if target is unreachable from source.

Function

shortestPathLength(n: int, edges: int[][], source: int, target: int) → int

Examples

Example 1

n = 5edges = [[0,1],[1,2],[0,3],[3,4],[4,2]]source = 0target = 2return = 2

The path 0 -> 1 -> 2 uses two edges, and no one-edge path connects 0 to 2.

Example 2

n = 4edges = [[0,1],[2,3]]source = 0target = 3return = -1

Vertices 0 and 3 belong to different connected components.

Example 3

n = 3edges = [[0,1]]source = 2target = 2return = 0

A vertex has distance 0 from itself.

Constraints

1 ≤ n ≤ 10^5.
0 ≤ edges.length ≤ 2 * 10^5.
Each edge contains two distinct vertices in the range [0, n - 1].
No undirected edge appears more than once.
0 ≤ source, target < n.