problems

problems/medium/group-transactions/solution.py

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+"""
+Transaction Grouper
+
+You're building a financial dashboard for a budgeting app. Users want
+to see their spending grouped by category with totals, so they can
+understand where their money is going each month.
+
+Example 1:
+    Input: transactions = [
+        {"amount": 50, "category": "food", "date": "2024-01-01"},
+        {"amount": 30, "category": "food", "date": "2024-01-02"},
+        {"amount": 100, "category": "transport", "date": "2024-01-01"}
+    ]
+    Output: {"food": 80, "transport": 100}
+    Explanation: food: 50+30=80, transport: 100
+
+Example 2:
+    Input: transactions = []
+    Output: {}
+    Explanation: No transactions means empty result
+
+Constraints:
+    - Each transaction has "amount" (positive int), "category" (str), "date" (str)
+    - Categories are case-sensitive
+    - Return categories in any order
+    - Amount is always positive
+"""
+
+
+def group_transactions(transactions: list[dict]) -> dict[str, int]:
+    """Return dictionary mapping each category to its total amount."""
+    pass  # Your implementation here
+