Track Highest-Earning Experience

You are building a core component for a real-time analytics system that tracks the profitability of experiences on a large online platform. Implement a function that processes a sequence of operations and returns the result of each query. You are given three arrays of equal length: - `operations[i]`: either `'U'` for an update or `'Q'` for a query - `experiences[i]`: the name of the experience involved in operation `i` - `deltas[i]`: the profit change for the experience if `operations[i] == 'U'`; otherwise this value is ignored Rules: - For an update operation `'U'`, add `deltas[i]` to the current total earnings of `experiences[i]` - For a query operation `'Q'`, return the name of the experience with the highest total earnings at that moment - If an experience has not been updated before, treat its earnings as `0` before applying its first update - If multiple experiences are tied for the highest earnings, returning any one of them is acceptable - You may assume each query happens after at least one update Return an array containing the answers for all query operations, in order. Example: - `operations = ['U', 'U', 'Q', 'U', 'Q']` - `experiences = ['GameA', 'GameB', '', 'GameA', '']` - `deltas = [5, 7, 0, 4, 0]` Processing: - Update `GameA` by `+5` → totals: `GameA = 5` - Update `GameB` by `+7` → totals: `GameB = 7` - Query → return `GameB` - Update `GameA` by `+4` → totals: `GameA = 9` - Query → return `GameA` Output: `['GameB', 'GameA']` Design an efficient solution for processing many updates and queries.