The Traveling Salesman Problem (TSP) is a classic optimization challenge that seeks the shortest possible route for a salesman to visit each city in a list exactly once and return to the origin city. 
We will use Guided Local Search (GLS) algorithm to solve this problem. 
Your task is to find a `heuristic` function for the GLS algorithm. This function will generate the `guide` matrix for the GLS algorithm.
Your goal is to minimize the objective, which is the average test tour distances for the salesman (called "score" or "objective" of solution).