1. Given a list of transactions, group by name and currency.

Sample Input

Id	Name	Amount	Currency
1	Puneet	200	INR
2	Puneet	3000	USD
3	Puneet	20	INR
4	Puneet	50	USD
5	Sahil	40	USD
6	Sahil	30	USD
7	Sahil	230	INR
8	Sahil	520	INR

Sample Output

Puneet	220	INR
Puneet	3050	USD
Sahil	750	INR
Sahil	70	USD

Java Code

// Grouping by name and currency, then summing amounts
Map<String, Map<String, Integer>> grouped = transactions.stream()
    .collect(Collectors.groupingBy(
        Transaction::getName,
        Collectors.groupingBy(
            Transaction::getCurrency,
            Collectors.summingInt(Transaction::getAmount)
        )
    ));

// Printing the result
grouped.forEach((name, currencyMap) -> {
    currencyMap.forEach((currency, totalAmount) -> {
        System.out.println(name + "\t" + totalAmount + "\t" + currency);
    });
});