Условие
LINQ's Join matches items from two sequences by a shared key, much like a database join. Here, customers are matched with their orders by customer id.
Customer i has id customer_ids[i] and name customer_names[i]. Each order is [customer_id, amount].
Join the two: for every customer with at least one order, add up the amounts of their orders. Customers without orders are left out, and orders whose customer id is unknown are ignored.
Implement join_customers_orders(customer_ids, customer_names, orders).
Input
customer_ids, customer_names: The customers (ids are distinct).
orders: [customer_id, amount] pairs.
Output
Return "<name>:<total>" for each customer with orders, sorted by total from highest to lowest, and by name (ordinal order) when totals are equal.
Ограничения
1 ≤ number of customers ≤ 10,000
0 ≤ number of orders ≤ 100,000; 1 ≤ amount ≤ 10^6
Примеры
Ввод:
orders = [
[1, 50],
[2, 30],
[1, 20]
]
customer_ids = [1, 2, 3]
customer_names = ["Ada", "Lin", "Bo"]
Ожидаемый вывод:
expected = ["Ada:70", "Lin:30"]Ввод:
std::vector<std::vector<long long>> orders = {
{1, 50},
{2, 30},
{1, 20}
};
std::vector<long long> customer_ids = {1, 2, 3};
std::vector<std::string> customer_names = {"Ada", "Lin", "Bo"};
Ожидаемый вывод:
std::vector<std::string> expected = {"Ada:70", "Lin:30"};Ввод:
long[][] orders = new long[][] {
new long[] {1, 50},
new long[] {2, 30},
new long[] {1, 20}
};
long[] customer_ids = new long[] {1, 2, 3};
string[] customer_names = new string[] {"Ada", "Lin", "Bo"};
Ожидаемый вывод:
string[] expected = new string[] {"Ada:70", "Lin:30"};Пояснение
Ada has two orders (50 + 20 = 70) and Lin one (30); Bo has none and is left out: ["Ada:70", "Lin:30"].
Ввод:
orders = [
[8, 40],
[7, 40],
[9, 99]
]
customer_ids = [7, 8]
customer_names = ["Zoe", "Max"]
Ожидаемый вывод:
expected = ["Max:40", "Zoe:40"]Ввод:
std::vector<std::vector<long long>> orders = {
{8, 40},
{7, 40},
{9, 99}
};
std::vector<long long> customer_ids = {7, 8};
std::vector<std::string> customer_names = {"Zoe", "Max"};
Ожидаемый вывод:
std::vector<std::string> expected = {"Max:40", "Zoe:40"};Ввод:
long[][] orders = new long[][] {
new long[] {8, 40},
new long[] {7, 40},
new long[] {9, 99}
};
long[] customer_ids = new long[] {7, 8};
string[] customer_names = new string[] {"Zoe", "Max"};
Ожидаемый вывод:
string[] expected = new string[] {"Max:40", "Zoe:40"};Пояснение
Both total 40, so they are ordered by name; the order for unknown id 9 is ignored: ["Max:40", "Zoe:40"].
Как подступиться
Сначала попробуйте сами, затем открывайте подсказки по одной.
Подсказка 1
First add up the order amounts per customer id.
Подсказка 2
Then go through the customers and keep those that have a total.
Подсказка 3
Sort by total descending, then by name in ordinal order.
Ожидаемая сложность
O(n log n) time, O(n) extra space
Ссылки
Это задание адаптировано для CodeUtility. Следуйте условию и ограничениям выше.