k-Path Problem: For every subset XV(G)of size k, Input:A graph G and positive integer k check if X is a k-path in G. Question:Is there a simple path on k vertices in G? k=4 [1]Michael R.Garey and David S.Johnson,Computers and intractability:A Guide to the Theory of NP- Completeness k-Path Problem： Input: A graph G and positive integer k Question: Is there a simple path on 𝑘 vertices in 𝐺? k=4 For every subset X⊆V(G) of size k, check if X is a k-path in G. [1] Michael R. Garey and David S. Johnson, Computers and intractability: A Guide to the Theory of NP￾Completeness