1129. Shortest Path with Alternating Colors

https://leetcode.com/problems/shortest-path-with-alternating-colors

Description

Consider a directed graph, with nodes labelled 0, 1, ..., n-1. In this graph, each edge is either red or blue, and there could be self-edges or parallel edges.

Each [i, j] in red_edges denotes a red directed edge from node i to node j. Similarly, each [i, j] in blue_edges denotes a blue directed edge from node i to node j.

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 doesn't exist).

Example 1:

**Input:** n = 3, red\_edges = [[0,1],[1,2]], blue\_edges = []
**Output:** [0,1,-1]

Example 2:

**Input:** n = 3, red\_edges = [[0,1]], blue\_edges = [[2,1]]
**Output:** [0,1,-1]

Example 3:

**Input:** n = 3, red\_edges = [[1,0]], blue\_edges = [[2,1]]
**Output:** [0,-1,-1]

Example 4:

**Input:** n = 3, red\_edges = [[0,1]], blue\_edges = [[1,2]]
**Output:** [0,1,2]

Example 5:

**Input:** n = 3, red\_edges = [[0,1],[0,2]], blue\_edges = [[1,0]]
**Output:** [0,1,1]

Constraints:

• 1 <= n <= 100

• red_edges.length <= 400

• blue_edges.length <= 400

• red_edges[i].length == blue_edges[i].length == 2

• 0 <= red_edges[i][j], blue_edges[i][j] < n

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