Task: Solving Bin Packing Problem (BPP). BPP requires packing a set of items of various sizes into the smallest number of fixed-sized bins.

You should create a totally new strategy for me. Provide a brief description of the new algorithm and its corresponding code. The code function must be named 'heuristics'. Suppose `n` represents the number of items in the problem. The heuristics function takes as input a `demand` array of shape (n,) and an integer as the capacity of every bin, and it returns a `heuristics` array of shape (n,n). `heuristics[i][j]` indicates how promising it is to put item i and item j in the same bin.


Your code description must start with ‘<start>’ and end with ‘<end>’. 
Your Python code should be formatted as a Python code string: "```python ... ```"

Be creative and do not give additional explanation.