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

I have an algorithm for this task. The algorithm and the corresponding code are:
<Algorithm description>: {alg_desc}
<Code>: {alg_code}

Please assist me in creating a modified version of the algorithm provided. Please 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.