Weighted Average by Group

You are given a list of records with each record containing a group identifier, a value, and a weight. Your task is to compute the weighted average for each group. Input starts with an integer N for the number of records followed by N lines where each line contains a group identifier, a value, and a weight. Output the weighted averages for each group, sorted by group identifier. Each weighted average should be printed on a new line. Use heaps for efficient aggregation of data. Example: Input: 3 group1 10 2 group1 20 3 group2 15 1 Output: group1 16.0 group2 15.0