Validate whether a given sequence is a Hamiltonian path
Company: Codeium
Role: Software Engineer
Category: Coding & Algorithms
Difficulty: medium
Interview Round: Take-home Project
You are given `strArr`, an array of **three strings** describing an undirected graph and a proposed vertex visit order:
1. `strArr[0]`: a comma-separated list of vertices in parentheses, e.g. `"(A,B,C)"`
2. `strArr[1]`: a comma-separated list of undirected edges in parentheses, e.g. `"(A-B,C-D)"`
3. `strArr[2]`: a comma-separated list of vertices representing the proposed path order, e.g. `"(C,A,B)"`
Task:
- Determine whether the proposed order is a **Hamiltonian path**: it must visit **every vertex in the graph exactly once**, and every consecutive pair in the order must be connected by an edge.
Output:
- Return `"yes"` if the order forms a Hamiltonian path.
- Otherwise, return the **first vertex in the given order where the path fails**, meaning the earliest vertex `order[i]` such that either:
- `order[i]` is not a vertex in the graph, or
- `order[i]` has already appeared earlier in the order, or
- there is **no edge** between `order[i-1]` and `order[i]` (for `i > 0`).
Assumptions/constraints:
- The graph has at least 2 vertices and is connected.
- Vertices are represented by single tokens like `A`, `B`, `X`, etc.
Examples:
- Input: `["(A,B,C)", "(B-A,C-B)", "(C,A,B)"]` → Output: `"yes"`
- Input: `["(X,Y,Z,Q)", "(X-Y,Y-Q,Y-Z)", "(Z,Y,Q,X)"]` → Output: `"Q"` (because there is no edge between `Q` and `X`)
Quick Answer: This question evaluates understanding of graph theory concepts—specifically Hamiltonian paths, graph representation parsing, and sequential edge validation— within the Coding & Algorithms domain and emphasizes practical application of graph traversal and validation rather than purely theoretical proofs.