- Difficulty: Medium
- Tags: LeetCode, Medium, Breadth-First Search, Graph, leetcode-1129, O(n + e)
Problem
You are given an integer n
, the number of nodes in a directed graph where the nodes are labeled from 0
to n - 1
. Each edge is red or blue in this graph, and there could be self-edges and parallel edges.
You are given two arrays redEdges
and blueEdges
where:
redEdges[i] = [ai, bi]
indicates that there is a directed red edge from nodeai
to nodebi
in the graph, andblueEdges[j] = [uj, vj]
indicates that there is a directed blue edge from nodeuj
to nodevj
in the graph.
Return an array answer
of length n
, where each answer[x]
is the length of the shortest path from node 0
to node x
such that the edge colors alternate along the path, or -1
if such a path does not exist.
Example 1:
Input: n = 3, redEdges = [[0,1],[1,2]], blueEdges = [] Output: [0,1,-1]
Example 2:
Input: n = 3, redEdges = [[0,1]], blueEdges = [[2,1]] Output: [0,1,-1]
Constraints:
1 <= n <= 100
0 <= redEdges.length, blueEdges.length <= 400
redEdges[i].length == blueEdges[j].length == 2
0 <= ai, bi, uj, vj < n